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Mass spectrometry imaging (MSI) of lipids within tissues has significant potential for both biomolecular discovery and histopathological applications. Conventional MSI technologies are, however, challenged by the prevalence of phospholipid regioisomers that differ only in the location(s) of carbon-carbon double bonds and/or the relative position of fatty acyl attachment to the glycerol backbone (i.e., sn position). The inability to resolve isomeric lipids within imaging experiments masks underlying complexity, resulting in a critical loss of metabolic information. Herein, ozone-induced dissociation (OzID) is implemented on a mobility-enabled quadrupole time-of-flight (Q-TOF) mass spectrometer capable of matrix-assisted laser desorption/ionization (MALDI). Exploiting the ion mobility region in the Q-TOF, high number densities of ozone were accessed, leading to similar to 1000-fold enhancement in the abundance of OzID product ions compared to earlier MALDI-OzID implementations. Translation of this uplift into imaging resulted in a 50-fold improvement in acquisition rate, facilitating large-area mapping with resolution of phospholipid isomers. Mapping isomer distributions across rat brain sections revealed distinct distributions of lipid isomer populations with region-specific associations of isomers differing in double bond and sn positions. Moreover, product ions arising from sequential ozone- and collision-induced dissociation enabled double bond assignments in unsaturated fatty acyl chains esterified at the noncanonical sn-1 position.

The role of sodium acetate in the synthesis of [Au(NHC)Cl] complexes was examined. The use of this base was also investigated for the activation of C-H and S-H bonds by experimental and computational methods. The synthetic use of NaOAc to assemble these complexes is applicable to a wide range of NHCs and proceeds under air, under mild conditions and using technical grade green solvents.

The intricate architecture of cell walls and the complex cross-linking of their components hinders some industrial and agricultural applications of plant biomass. Xylan is a key structural element of grass cell walls, closely interacting with other cell wall components such as cellulose and lignin. The main branching points of grass xylan, 3-linked l-arabinosyl substitutions, can be modified by ferulic acid (a hydroxycinnamic acid), which cross-links xylan to other xylan chains and lignin. XAX1 (Xylosyl arabinosyl substitution of xylan 1), a rice (Oryza sativa) member of the glycosyltransferase family GT61, has been described to add xylosyl residues to arabinosyl substitutions modified by ferulic acid. In this study, we characterize hydroxycinnamic acid-decorated arabinosyl substitutions present on rice xylan and their cross-linking, in order to decipher the role of XAX1 in xylan synthesis. Our results show a general reduction of hydroxycinnamic acid-modified 3-linked arabinosyl substitutions in xax1 mutant rice regardless of their modification with a xylosyl residue. Moreover, structures resembling the direct cross-link between xylan and lignin (ferulated arabinosyl substitutions bound to lignin monomers and dimers), together with diferulates known to cross-link xylan, are strongly reduced in xax1. Interestingly, apart from feruloyl and p-coumaroyl modifications on arabinose, putative caffeoyl and oxalyl modifications were characterized, which were also reduced in xax1. Our results suggest an alternative function of XAX1 in the transfer of hydroxycinnamic acid-modified arabinosyl substitutions to xylan, rather than xylosyl transfer to arabinosyl substitutions. Ultimately, XAX1 plays a fundamental role in cross-linking, providing a potential target for the improvement of use of grass biomass.

Wheat bran incorporation into biscuits may increase their nutritional value, however, it may affect dough rheology and baking performance, due to the effect of bran particles on dough structure and an increase in water absorption. This study analyzed the enrichment effect of wheat bran and arabinoxylans, the most important non-starch polysaccharides found in whole wheat flour, on dough rheology and thermal behaviour during processing of rotary-moulded biscuits. The objective was to understand the contribution of arabinoxylans during biscuit-making and their impact when incorporated as wheat bran. Refined flour was replaced at 25, 50, 75, or 100% by whole flour with different bran particle sizes (fine: 4% &gt, 500 μm, coarse: 72% &gt, 500 μm). The isolated effect of arabinoxylans was examined by preparing model flours, where refined flour was enriched with water-extractable and water-unextractable arabinoxylans. Wheat bran had the greatest impact on dough firmness and arabinoxylans had the greatest impact on the elastic response. The degree of starch gelatinization increased from 24 to 36% in biscuits enriched with arabinoxylans or whole flour and coarse bran. The microstructural analysis (SEM, micro-CT) suggested that fibre micropores may retain water inside their capillaries which can be released in a controlled manner during baking.

O-methyltransferases are ubiquitous enzymes involved in biosynthetic pathways for secondary metabolites such as bacterial antibiotics, human catecholamine neurotransmitters, and plant phenylpropanoids. While thousands of putative O-methyltransferases are found in sequence databases, few examples are functionally characterized. From a pathway engineering perspective, however, it is crucial to know the substrate and product ranges of the respective enzymes to fully exploit their catalytic power.In this study, we developed anin vitroprototyping workflow that allowed us to screen ~30 enzymes against five substrates in three days with high reproducibility. We combinedin vitrotranscription/translation of the genes of interest with a microliter-scale enzymatic assay in 96-well plates. The substrate conversion was indirectly measured by quantifying the consumption of the S-adenosyl-L-methionine co-factor by time-resolved fluorescence resonance energy transfer rather than time-consuming product analysis by chromatography. This workflow allowed us to rapidly prototype thus-far uncharacterized O-methyltransferases for future use as biocatalysts.

New mononuclear complexes [Mn(NO3)(sac)(H2O)(bzimpy)]center dot 2DMF (Mn), [Fe(sac)(2)(H2O)(bzimpy)]center dot 2H(2)O (Fe), [Co(bzimpy)(2)](sac)(2)center dot 2H(2)O (Co), [Ni(bzimpy)(2)](sac)(2)center dot H2O center dot i-PrOH (Ni) and [Cu(sac)(2)(bzimpy)]center dot 3DMF (Cu) (sac = saccharinate and bzimpy = 2,6-bis(2-benzimidazolyl)pyridine) were synthesized and structurally characterized by elemental analysis, UV-Vis, IR, ESI-MS and X-ray diffraction. The anticancer activity of the metal complexes against A549 (lung), MCF-7 (breast), HT29 (colon) cancer cells and MCF10A (normal human breast epithelial) cells was tested and compared with those of cisplatin and bzimpy. The complexes displayed potent cytotoxic activity especially in MCF-7 and A549 cell lines, but they were practically inactive against the normal cells. Mechanistic studies with Mn and Cu complexes on A549 cells indicated that the complexes induced G0/G1 arrest. Both complexes increased intracellular ROS (reactive oxygen species) levels and successfully caused both mitochondrial dysfunction and doublestrand DNA breaks. The up-regulated Bax and down-regulated Bcl-2 expression levels, caspase-3/7 activation and reduced Fas expression indicated that Mn and Cu induced ROS-dependent mitochondria-mediated intrinsic apoptosis in A549 cells. (C) 2020 Elsevier Masson SAS. All rights reserved.

Polylactide (PLA) is a high potential bioplastic that can replace oil‐based plastics in a number of applications. To date, in spite of its known toxicity, a tin catalyst is used on industrial scale which should be replaced by a benign catalyst in the long run. Germanium is known to be unharmful while having similar properties as tin. Only few germylene catalysts are known so far and none has shown the potential for industrial application. We herein present Ge complexes in combination with zinc and copper, which show amazingly high polymerization activities for lactide in bulk at 150 °C. By systematical variation of the complex structure, proven by single‐crystal XRD and DFT calculations, structure–property relationships are found regarding the polymerization activity. Even in the presence of zinc and copper, germanium acts as the active site for polymerizing probably through the coordination–insertion mechanism to high molar mass polymers., On the route towards a benign production of PLA, we came across Germanium. With its similar properties to tin due to its close position in the periodic table, germanium, being completely nontoxic, is a promising, but so far rather neglected candidate for an alternative catalyst for industrial lactide polymerization. With high molar masses after 1 h of polymerization at 150 °C in bulk, these examples show the high efficiency germanium catalysts can reach (see scheme).

Mass spectrometry imaging (MSI) enables the spatial distributions of molecules possessing different mass‐to‐charge ratios to be mapped within complex environments revealing regional changes at the molecular level. Even at high mass resolving power, however, these images often reflect the summed distribution of multiple isomeric molecules, each potentially possessing a unique distribution coinciding with distinct biological function(s) and metabolic origin. Herein, this chemical ambiguity is addressed through an innovative combination of ozone‐induced dissociation reactions with MSI, enabling the differential imaging of isomeric lipid molecules directly from biological tissues. For the first time, we demonstrate both double bond‐ and sn‐positional isomeric lipids exhibit distinct spatial locations within tissue. This MSI approach enables researchers to unravel local lipid molecular complexity based on both exact elemental composition and isomeric structure directly from tissues.

Lipids are a large and highly diverse family of biomolecules, which play essential structural, storage and signalling roles in cells and tissues. Although traditional mass spectrometry (MS) approaches used in lipidomics are highly sensitive and selective, lipid analysis remains challenging due to the chemical diversity of lipid structures, multiple isobaric species and incomplete separation using many forms of chromatography. Ion mobility (IM) separates ions in the gas phase based on their physicochemical properties. Addition of IM to the traditional lipidomic workflow both enhances separation of complex lipid mixtures, beneficial for lipid identification, and improves isomer resolution. Herein, we discuss the recent developments in IM-MS for lipidomics.

International audience; Herein we report the synthesis of new ditopic ligands, which consist of a phenoxy group and N,N,N'trisubstituted amidines linked by a methylene spacer (L1-L4). Their coordination chemistry has been studied/investigated with Zn(II) and Al(III). Alkane elimination route between the phenol-amidine proligands (L1H-L4H) and Et2Zn led to dinuclear complexes [(L1-L4)ZnEt]2 (1a-4a) in which the Zn centers are chelated by phenoxyamidine ligands and bridged through the oxygen atom of the phenoxy groups. Salt metathesis reaction between two equivalents of the sodium amidine phenate L1Na and ZnCl2 led to a bis-chelate chiral spiro-complex (L12Zn) 1a'. Analogous alkane elimination route between AlMe3 and the phenol-amidine proligands L1H-L4H allowed the preparation of the mononuclear complexes [(L1-L4)AlMe2] (1b-4b). The phenoxyamidine-Al and Zn complexes have been characterized by NMR spectroscopy, elemental analysis and/or high resolution ESI-MS. The solid state structures of the proligands [L1H2][Br] and L2H as well as of six complexes have been established by single crystal X-ray diffraction analysis. Fluxional properties of the proligands L1H-L2H and of the complexes 1a and 2b have been investigated by VT NMR experiments. In the presence of an alcohol source, complexes 1a-4a and 1b-4b were used as initiators for the controlled ring-opening polymerization (ROP) of rac-lactide to afford atactic polylactic acid (PLA).

Hydrolysis of Transferin (Tf), a glycoprotein consisting of 679 amino acids and three glycan chains, has been examined in the presence of Ce(IV)-substituted Keggin polyoxometalate [CeIV(α-PW11O39)2]10− (Ce-K POM). Incubation at pH = 7.4 and at 37 °C resulted in selective fragmentation of the Tf after 24 h, which was followed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE). After 5 days of incubation nearly 90% of Tf was hydrolyzed, giving 9 fragments with molecular weight (Mw) in the range between 13.7 and 69.5 kDa. Under the same conditions, the sample of Tf which did not contain the Ce-K POM, showed only 7% of background hydrolysis. The interactions between Ce-K and Tf were studied by tryptophan fluorescence, circular dichroism (CD) and 31P Nuclear magnetic resonance (NMR) spectroscopy. The association constant (Ka) for the interaction was calculated to be 3.2 × 104 M−1 from tryptophan quenching studies. CD spectroscopy revealed that binding of Ce-K to Tf resulted in significant secondary structure changes, mainly affecting the alpha-helical content of the protein. 31P NMR spectroscopy showed that in the presence of the Tf partial reduction of Ce(IV) to Ce(III) occurred, which did not affect the overall structure of the Keggin POM. ispartof: Polyhedron vol:170 pages:570-575 status: published

Reaction of the arylchlorosilylene-NHC adduct ArSi(NHC) Cl [Ar= 2,6-Trip(2)C(6)H(3); NHC=(MeC)(2)(NMe)(2)C:] 1 with one molar equiv of lithium diphenylphosphanide affords the first stable NHC-stabilized acyclic phosphinosilylene adduct 2 (ArSi(NHC)PPh2), which could be structurally characterized. Compound 2, when reacted with one molar equiv selenium and sulfur, affords the silanechalcogenones 4a and 4b (ArSi(NHC)(= E)PPh2, 4a: E= Se, 4b: E= S), respectively. Conversion of 2 with an excess of Se and S, through additional insertion of one chalcogen atom into the Si - P bond, leads to 3a and 3b (ArSi(NHC)(= E)-E-P(= E)Ph-2, 3a: E= Se, 3b: E= S), respectively. Additionally, the exposure of 2 to N2O or CO2 yielded the isolable NHC-stabilized silanone 4c, Ar(NHC)(Ph2P) Si=O.

Aim of this study was to produce hydrophilic breathable polyurethane membranes providing antibacterial property permanently by incorporation of a quaternary ammonium salt diol (QAS). The study was carried out by synthesis of nine different polyurethanes by solution polymerization through variations of their QAS and isocyanate contents. Fully amorphous membranes at a thickness of 30m were produced from the synthesized polymers and their thermal and morphological characteristics were determined. The effect of morphological structures on the membrane water vapor transmission rates (WVTR) and antibacterial properties were correlated. The WVTR increased with the increased temperature in all membranes over 10-40 degrees C, all produced membranes showed water resistance up to a pressure of 2100 cmH2O and WVTR values above 60g/m(2) h at 30 degrees C. The WVTR increased by increasing amount of QAS including cationic groups and decreased by increasing isocyanate amount reducing the molecular chain flexibility. In addition, while the unmodified membranes did not show any antibacterial activity, the QAS-added membranes provided significant inactivation against Staphylococcus aureus and Escherichia coli of about 104CFU within 5h of contact time. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47133.

Nine GtfB-like 4,6-α-glucanotransferases (4,6-α-GTs) (represented by GtfX of L. aviarius subsp. aviarius DSM 20655) were identified to show distinct characteristics in conserved motifs I-IV. In particular, the "fingerprint" Tyr in motif III of these nine GtfB-type 4,6-α-GTs was found to be replaced by a Trp. In L. aviarius subsp. aviarius DSM20655, a second GtfB-like protein (GtfY), containing the canonical GtfB Tyr residue in motif III, was located directly upstream of GtfX. Biochemical characterization revealed that both GtfX and GtfY showed GtfB-like 4,6-α-GT activity, cleaving (α1→4) linkages and catalyzing the synthesis of (α1→6) linkages. Nonetheless, they differ in product specificity; GtfY only synthesizes consecutive (α1→6) linkages, yielding linear α-glucan products, but GtfX catalyzes the synthesis of (α1→6) linkages predominantly at branch points (22%) rather than in linear segments (10%). The highly branched α-glucan produced by GtfX from amylose V is resistant to digestion by α-amylase, offering great potential as dietary fibers.

The fructophilic bacterium Lactobacillus kunkeei has promising applications as probiotics promoting the health of both honey bees and humans. Here, we report the synthesis of a highly branched dextran by L. kunkeei DSM 12361 and biochemical characterization of a GH70 enzyme (GtfZ). Sequence analysis revealed that GtfZ harbors two separate catalytic cores (CD1 and CD2), predicted to have glucansucrase and branching sucrase specificity, respectively. GtfZ-CD1 was not characterized biochemically due to its unsuccessful expression. With only sucrose as substrate, GtfZ-CD2 was found to mainly catalyze sucrose hydrolysis and leucrose synthesis. When dextran was available as acceptor substrate, GtfZ-CD2 displayed an efficient transglycosidase activity with sucrose as donor substrate. Kinetic analysis showed that the GtfZ-CD2-catalyzed transglycosylation reaction follows a Ping Pong Bi Bi mechanism, indicating the in-turn binding of donor and acceptor substrates in the active site. Structural characterization of the products revealed that GtfZ-CD2 catalyzes the synthesis of single glucosyl (α1 → 3) linked branches onto dextran, resulting in the production of highly branched comb-like α-glucan products. These (α1 → 3) branches can be formed on adjacent positions, as shown when isomaltotriose was used as acceptor substrate. Homology modeling of the GtfZ-CD1 and GtfZ-CD2 protein structure strongly suggests that amino acid differences in conserved motifs II, III, and IV in the catalytic domain contribute to product specificity. Our present study highlights the ability of beneficial lactic acid bacteria to produce structurally complex α-glucans and provides novel insights into the molecular mechanism of an (α1 → 3) branching sucrase.

Steviol glycosides from the leaves of the plant Stevia rebaudiana are high-potency natural sweeteners but suffer from a lingering bitterness. The Lactobacillus reuteri 180 wild-type glucansucrase Gtf180-ΔN, and in particular its Q1140E-mutant, efficiently α-glucosylated rebaudioside A (RebA), using sucrose as donor substrate. Structural analysis of the products by MALDI-TOF mass spectrometry, methylation analysis and NMR spectroscopy showed that both enzymes exclusively glucosylate the Glc(β1→C-19 residue of RebA, with the initial formation of an (α1→6) linkage. Docking of RebA in the active site of the enzyme revealed that only the steviol C-19 β-D-glucosyl moiety is available for glucosylation. Response surface methodology was applied to optimize the Gtf180-ΔN-Q1140E-catalyzed α-glucosylation of RebA, resulting in a highly productive process with a RebA conversion of 95% and a production of 115 g/L α-glucosylated products within 3 h. Development of a fed-batch reaction allowed further suppression of α-glucan synthesis which improved the product yield to 270 g/L. Sensory analysis by a trained panel revealed that glucosylated RebA products show a significant reduction in bitterness, resulting in a superior taste profile compared to RebA. The Gtf180-ΔN-Q1140E glucansucrase mutant enzyme thus is an efficient biocatalyst for generating α-glucosylated RebA variants with improved edulcorant/organoleptic properties.

New bismuth(III) bromine compounds of the heterocyclic thioamides were prepared and structurally characterized. The reaction of heterocyclic thioamides with bismuth(III) bromide resulted in the formation of the {[BiBr2(mu(2)-Br)(MMI)(2)](2)center dot CH3COCH3 center dot H2O} (1), {[BiBr2(MBZIM)(4)]center dot Br center dot 2H(2)O} (2), {[BiBr2(mu(2)-Br)(tHPMT)(2)](2)center dot CH3CN} (3), {[BiBr2(mu(2)-Br)(PYT)(2)](2)center dot CH3CN} (4) and {[BiBr2(mu(2)-Br)(MBZT)(2)](2) 2CH(3)OH} (5) complexes (MMI: 2-mercapto-1-methylimidazole, MBZIM: 2-mercaptobenzimidazole, tHPMT: 2-mercapto-3,4,5,6-tetrahydro-pyrimidine, PYT: 2-mercaptopyridine and MBZT: 2-mercaptobenzothiazole). The complexes 1-5 were characterized by melting point (m.p.), elemental analysis (c.a.), molar conductivity, Fourier-transform infrared (FT-IR), Fourier-transform Raman (FT-Raman), nuclear magnetic resonance (H-1 and (CNMR)-C-13) spectroscopy, UV-Vis spectroscopy and thermogravimetric-differential thermal analysis (TG-DTA). The molecular structures of 1-5 were determined by single-crystal X-ray diffraction. Complex 2 is a first ionic monomuclear octahedral bismuth(III) bromide, while the complexes 1,3-5 are the first examples of dinuclear bismuth(III) bromide derivatives. Complexes 1-5 were evaluated in terms of their in vitro cytotoxic activity against human adenocarcinoma breast (MCF-7) and cervix (HeLa) cells. The toxicity on normal human fetal lung fibroblast cells (MRC-5) was also evaluated. Moreover, the complexes 1-5 and free heterocyclic thioamide ligands were studied upon the catalytic peroxidation of the linoleic acid by the enzyme lipoxygenase (LOX). Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114Z457] (a) I.I.O. and M.C. acknowledge the financial support from The Scientific and Technological Research Council of Turkey (TUBITAK, Project No. 114Z457). (b) CNB and SKH would like to thank the Unit of Bioactivity Testing of Xenobiotics of the University of Ioannina for providing access to their facilities. (c) The International Graduate Program in 'Biological Inorganic Chemistry', which operates at the University of Ioannina within the collaboration of the Departments of Chemistry of the Universities of Ioannina, Athens, Thessaloniki, Patras, Crete and the Department of Chemistry of the University of Cyprus (http://bic.chem.uoi.gr/BIC-En/index-en.html), is acknowledged for the stimulating discussion forum.

Viscosity of cereal beta-glucan during digestion is considered to be a vital factor for its health effects. Thus, studies on solution properties and gelation are essential for understanding the mechanisms of the beta-glucan functionality. The aim of this study was to investigate the effect of the dissolution temperature on gelation of cereal beta-glucan at low concentrations that are relevant for food products. The rheological properties of oat and barley beta-glucans (OBG and BBG) using three dissolution temperatures (37 degrees C, 57 degrees C and 85 degrees C) at low concentration (1.5% and 1%, respectively) were studied for 7 days. Additionally, the beta-glucans were oxidised with 70 mM H2O2 and 1 mM FeSO4 x 7H(2)O as a catalyst, to evaluate the consequence of oxidative degradation on the gelation properties. The study showed that dissolution at 85 degrees C did not result in gelation. The optimal dissolution temperature for gelation of OBG was 37 degrees C and for gelation of BBG 57 degrees C. At these temperatures, also the oxidised OBG and BBG gelled, although the gel strength was somewhat lower than in the non-oxidised ones. Gelation was suggested to require partial dissolution of beta-glucan, which depended on the molar mass and aggregation state of the beta-glucan molecule. Therefore, the state of beta-glucan in solution and its thermal treatment history may affect its technological and physiological functionality. (C) 2017 Elsevier Ltd. All rights reserved.

In contrast to the extensively investigated beta-turn conformation in peptides and proteins, single and multiple gamma-turns have been much less commonly studied. Single and non-contiguous multiple gamma-turns have been relatively often authenticated in small cyclic peptides, but these important peptide main-chain reversal motifs have not been examined carefully either in linear peptides or in globular proteins. This Perspective article summarizes literature data on this aspect of peptide stereochemistry, expanding the discussion also to the rarely found, contiguous multiple gamma-turns which generate incipient or fully-developed 2.2(7)-(gamma-)helices. Unpublished results of recent research activities on this topic ongoing in our laboratories are also briefly outlined.

A series of new mercury(II) azine Schiff base complexes have been synthesized and characterized from the initial use of phenyl-2-pyridyl ketone azine in Hg-II chemistry. The synthetic/crystallization technique utilized involved the use of a branched tube, where temperature differential allowed for the slow crystallization of the products. The synthesized compounds are the mononuclear [Hg(L)Cl-2] (1), [Hg(L)Br-2] (2), [Hg(L)(NO2)(2)] (3), and the dinuclear [Hg-2(mu-L)(SCN)(4)] (4) coordination compounds, as well as a 1D coordination polymer [Hg(L)(mu-I)(2)HgI2](n) (5) (L = phenyl-2-pyridyl ketone azine). From the X-ray data, it is evident that this versatile ligand functions as a bi- or tridentate chelate, and is also able to bridge two H-II centers. The crystal structures of 1 and 2 are similar, both containing two crystallographically independent Hg-II molecules, one tetrahedrally coordinated and one exhibiting trigonal bipyramidal geometry. The heptacoordinated Hg-II center in 3 adopts a distorted capped trigonal prismatic coordination sphere, while in the dinuclear complex 4, the metal ions are bridged via the bis(bidentate) L and each center is also bound to two S-bonded thiocyanate units. The one-dimensional coordination polymer in 5 consists of a tetrahedral HgI4 and a trigonal bipyramidal HgN3I2 chromophore unit, bridged by mu-I- bridges. The thermal stability of the crystal lattice in 1-5 follows the pattern 3 > 1 > 2 > 5 > 4, as studied by TG/DTA, while the TG data of 1,2, and 5 are similar, but different than the respective ones for 3 and 4, between which important similarities are observed. In the solid state, the ligand and compounds 1-5 exhibit intraligand pi -> pi* fluorescence at room temperature. University of Tabriz Research Council Council of Scientific & Industrial Research (CSIR) - India Research Corporation for Science Advancement

Fluorinated room temperature ionic liquids (FRTILs) represent a class of solvent media that are attracting great attention due to their IL-specific properties as well as features stemming from their fluorous nature. Medium-to-long fluorous tails constitute a well-defined apolar moiety in the otherwise polar environment. Similarly to the case of alkyl tails, such chains are expected to result in the formation of self-assembled fluorous domains. So far, however, no direct experimental observation has been made of the existence of such structural heterogeneities on the nm scale. We report here the first experimental evidence of the existence of mesoscopic spatial segregation of fluorinated domains, on the basis of highly complementary X-ray and neutron scattering data sets (highlighting the importance of the latter probe) and NMR spectroscopy. Data are interpreted using atomistic molecular dynamics simulations, emphasizing the existence of a self-assembly mechanism that delivers segregated fluorous domains, where preferential solubilisation of fluorinated compounds can occur, thus paving the way for several smart applications.

The reactions of anionic platinum carbonyl Chini clusters [Pt3n(CO)6n](2-) [n = 2 (1), 3 (2), 4 (3)] with Ag(IPr)Cl [IPr = C3N2H2(C6H3(i)Pr2)2] afford the neutral acid-base Lewis adducts [Pt9(CO)18(AgIPr)2] (4) and [Pt6(CO)12(AgIPr)2] (5). These are thermally transformed into the homometallic heteroleptic neutral cluster [Pt3(CO)4(IPr)2] (6). Alternatively, 6 can be obtained from the reactions of 1-3 with an excess of the free IPr carbene ligand. The formation of 6 is sometimes accompanied by trace amounts of [Pt4(CO)4(IPr)3] (7). The reaction of 6 with free IPr affords the closely related [Pt3(CO)3(IPr)3] (8) heteroleptic cluster by substitution of the unique terminal CO ligand with a third IPr ligand. The reactions of 1-3 with Ag(IMes)Cl [IMes = C3N2H2(C6H2Me3)2] proceed differently from those involving Ag(IPr)Cl. Indeed, the only product isolated after workup is the bimetallic tetranuclear cluster [Pt3(CO)3(IMes)3(AgCl)] (9). 9 slowly reacts under a CO atmosphere, resulting in the pentanuclear [Pt5(CO)7(IMes)3] (10) complex. All of the new clusters 4-10 have been spectroscopically characterized and their molecular structures determined by X-ray crystallography. 4 and 5 retain the original trigonal-prismatic structures of the parent anionic Chini clusters, which are capped by two [Ag(IPr)](+) moieties. Conversely, 6-9 are based on a Pt3 triangular core decorated by CO and N-heterocyclic carbene ligands as well as Pt(CO) (in the case of 7) and AgCl (9) moieties. 10 displays an edge-bridged tetrahedral geometry.

Alkali metal salts of redox-active formazanate ligands were prepared, and their structures in the solid-state and in solution are determined. The nitrogen-rich [NNCNN] backbone of formazanates results in a varied coordination chemistry, with both the internal and terminal nitrogen atoms available for bonding with the alkali metal. The potassium salt K[PhNNC(p-tol)NNPh]center dot 2THF (1-K) is dimeric in the solid state and even in THF solution, as a result of the K atom bridging via interaction with a terminal N atom and the aromatic ring of a second unit. Conversely, for the compounds Na[MesNNC(CN)NNMes]center dot 2THF (2-Na) and Na[PhNNC(Bu-t)NNPh] (3-Na) polymeric and hexameric structures are found in the solid state respectively. The preference for binding the alkali metal through internal N atoms (1-K and 2-Na) to give a 4-membered chelate, or via internal/external N atoms (5-membered chelate in 3-Na), contrasts with the 6-membered chelate mode observed in our recently reported formazanate zinc complexes.

The probiotic bacterium Lactobacillus reuteri 121 produces a complex, branched (1 -> 4, 1 -> 6)-alpha-d-glucan as extracellular polysaccharide (reuteran) from sucrose (Suc), using a single glucansucrase/glucosyltransferase (GTFA) enzyme (reuteransucrase). To gain insight into the reaction/product specificity of the GTFA enzyme and the mechanism of reuteran formation, incubations with Suc and/or a series of malto-oligosaccharides (MOSs) (degree of polymerization (DP2-DP6)) were followed in time. The structures of the initially formed products, isolated via high-performance anion-exchange chromatography, were analyzed by matrix-assisted laser-desorption ionization time-of-flight mass spectrometry and 1D/2D H-1/C-13 NMR spectroscopy. Incubations with Suc only, acting as both donor and acceptor, resulted in elongation of Suc with glucose (Glc) units via alternating (alpha 1 -> 4) and (alpha 1 -> 6) linkages, yielding linear gluco-oligosaccharides up to at least DP similar to 12. Simultaneously with the ensemble of oligosaccharides, polymeric material was formed early on, suggesting that alternan fragments longer than DP similar to 12 have higher affinity with the GTFA enzyme and are quickly extended, yielding high-molecular-mass branched reuteran (4 x 10(7) Da). MOSs (DP2-DP6) in the absence of Suc turned out to be poor substrates. Incubations of GTFA with Suc plus MOSs as substrates resulted in preferential elongation of MOSs (acceptors) with Glc units from Suc (donor). This apparently reflects the higher affinity of GTFA for MOSs compared with Suc. In accordance with the GTFA specificity, most prominent products were oligosaccharides with an (alpha 1 -> 4)/(alpha 1 -> 6) alternating structure.

The chemical composition and the structural features of macromolecular components from red grape skins (variety Touriga Nacional) have been evaluated. The results of chemical analyses revealed the following contents of the main constituents: cellulose (20.8%), hemicelluloses (12.5%), proteins (18.8%), tannins (13.8%), extractives soluble in dichloromethane (5.0%) and ash (7.8%). Cellulose of grape skins is typical cellulose I polymorph with a degree of crystallinity of 66.1% as assessed by X-ray scattering. The hemicelluloses were analyzed by neutral sugars analysis, methylation analysis and 1D/2D H-1 NMR. The water-soluble compounds (26.4%) are composed mainly of monomeric sugars (glucose and fructose) and a complex mixture of hemicelluloses, the most abundant being pectin and acetylated glucomannan. The major part of structural polysaccharides (cellulose, xylan, xyloglucan, etc.) is embedded in cuticular layer and is poorly accessible to the acid hydrolysis. The cuticular substances contributed to ca. 8.5% of grape skins and their chemical structure has been evaluated by methanolysis. The possibility of comprehensive utilization of grape skins has been discussed. (C) 2012 Elsevier B.V. All rights reserved.

Several ruthenium(II)-chloro-dimethylsulfoxide complexes with formulae [RuCl2(DMSO)(k(3)-L-1)] or [RuCl(DMSO)(k(4)-L-2)](+), where L-1=[9]aneS(3) (2) or ttbt (5) and L-2=[12]aneS(4) (3), [14]aneS(4) (4) or [14]aneN(4) (6), have been synthesized from cis,fac-[RuCl2(S-DMSO)(3)(O-DMSO)] (1) and the respective macrocycle. They were spectroscopically characterized by FT-IR, FT-Raman, NMR, and UV/Vis. Particular attention was given to fac-[RuCl2(DMSO)(k(3)-ttbt)] (5), the first octahedral complex of ttbt, which was also studied by DFT calculations. The behavior of the complexes in coordinating solvents water, acetonitrile, and dimethylsulfoxide was studied to understand their reactivity and predict the resulting ions formed in solution. The role of the counter ion (Cl(-)vs. ) was also evaluated. The results indicate that the chosen macrocycle, the counter-ion, and the solvent have a direct impact on the chemical species formed in solution.

Cordyceps militaris dried fruiting bodies were extracted with 5% KOH solution. The extract was purified by freeze-thawing treatment, and dialysis (100 kDa), giving rise to a homogeneous polysaccharide (M-w 23,000 Da). Its monosaccharide composition was mannose (56.7%), galactose (34.5%), and glucose (8.8%). The anomeric configurations were determined by their coupling constants. A complex polysaccharide was identified by NMR and methylation analysis. The HSQC spectrum showed signals at delta 107.7/5.06 and 106.1/5.14; 105.9/5.12 relative to beta-D-Galf, and O-2-substituted beta-D-Galf units, respectively. The sign at delta 104.4/5.21 corresponded to alpha-D-Galf. Other signals corresponded to alpha-D-Manp O-6- and O-2-substituted (delta 100.2/4.94; 100.5/5.27; 100.6/5.23; 100.7/5.16), and alpha-D-Manp 2,6-di-O-substituted (from delta 99.3 to 99.9). The main linkages, confirmed by methylation analysis, showed the derivatives: 2,3,4-Me-3-Manp (11.9%) and 3,4,6-Me-3-Manp (28.6%). The branches were (1 -> 6)-linked-alpha-D-Manp or (1 -> 2)-linked-beta-D-Galf, terminating with beta-D-Galf, alpha-D-Galf, alpha-D-Galp, or alpha-D-Manp. 42.7% of the partially hydrolyzed product consisted of 3,4,6-Me-3-Manp, suggesting a (1 -> 2)-linked backbone. (C) 2013 Elsevier Ltd. All rights reserved.

11 páginas.-- 5 figuras.-- 1 tabla.-- 47 referencias.-- The following supplemental materials are available in the https://doi.org/10.1104/pp.16.02012, Lignin is an abundant aromatic plant cell wall polymer consisting of phenylpropanoid units in which the aromatic rings display various degrees of methoxylation. Tricin [5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one], a flavone, was recently established as a true monomer in grass lignins. To elucidate the incorporation pathways of tricin into grass lignin, the metabolites of maize (Zea mays) were extracted from lignifying tissues and profiled using the recently developed ‘candidate substrate product pair’ algorithm applied to ultra-high-performance liquid chromatography and Fourier transform-ion cyclotron resonance-mass spectrometry. Twelve tricin-containing products (each with up to eight isomers), including those derived from the various monolignol acetate and p-coumarate conjugates, were observed and authenticated by comparisons with a set of synthetic tricin-oligolignol dimeric and trimeric compounds. The identification of such compounds helps establish that tricin is an important monomer in the lignification of monocots, acting as a nucleation site for starting lignin chains. The array of tricin-containing products provides further evidence for the combinatorial coupling model of general lignification and supports evolving paradigms for the unique nature of lignification in monocots. Lignin is one of the major components in plant cell walls and is deposited predominantly in the walls of secondarily thickened cells. It is a complex phenylpropanoid polymer composed primarily of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units derived from the monolignols p-coumaryl 2h, coniferyl 2g, and sinapyl 2s alcohols, respectively (Fig. 1; Freudenberg and Neish, 1968). These monolignols are biosynthesized in the cytoplasm and translocated to the cell wall, where they are oxidized by laccases and peroxidases to monolignol radicals (Boerjan et al., 2003; Dixon and Reddy, 2003; Ralph et al., 2004b; Vanholme et al., 2008, 2010; Bonawitz and Chapple, 2010; Mottiar et al., 2016). The polymer can be started by radical coupling between two monolignol radicals to form a dehydrodimer from which the chain extends by endwise polymerization with additional monolignols, producing β-O-4-, β-5-, β-1-, and β-β-linked units in the lignin. Two growing oligomers also may radically couple to increase the polymer size, producing 4-O-5- and 5-5-linked units. During such radical coupling reactions, therefore, the monomer-derived units are linked together via various C-C and C-O bonds with different frequencies depending primarily on the monomer distribution and supply (Ralph et al., 2004b)., This work was supported by the Department of Energy Great Lakes Bioenergy Research Center (grant no. DE–FC02–07ER64494 to W.L., F.L., and J.R.), by Stanford University’s Global Climate and Energy Program (to J.R., K.M., and W.B.), by the Institute for the Promotion of Innovation through Science and Technology in Flanders via the SBO project Bioleum (to W.B. and K.M.), by the China Scholarship Council's State Education Department for his Ph.D. work in the Department of Biological System Engineering, University of Wisconsin, Madison (to W.L.).

The bovine milk fat globule membrane (MFGM) has many associated biological activities, many of which are linked with specific carbohydrate structures of MFGM glycoconjugates. Bovine buttermilk is a commercially viable source of MFGM and is an under-valued by-product of butter making. However, the changes in buttermilk glycosylation over the course of lactation have not been extensively investigated. In this study, buttermilk was generated from three individual multiparous cows at 13 time points over the first three months of lactation. Buttermilk glycosylation was profiled using lectin microarrays and lectin blotting. Suggested differences in glycosylation, including N-glycosylation, sialylation and fucosylation, were observed between early and late time points and between individual animals. Overall, these data suggest temporal changes in the glycosylation of buttermilk proteins which may have an important impact on commercial isolation of glycosylated ingredients.

The dithia/diselena meso-tetraarylporphyrins have a lesser tendency to form metal complexes because of the larger size of the heteroatom(s), which shrinks the cavity size, and the heteroatoms also have poor coordinating ability to bind metal ions. The first example of a rhenium(I) tricarbonyl complex of 21,23-diselenaporphyrin was synthesized by treating 5,10,15,20-tetra-p-tolyl-21,23-diselenaporphyrin with Re(CO)(5)Cl in chlorobenzene at reflux temperature and its structural properties were compared with our earlier reported rhenium(I) complex of tetraaryl-21,23-dithiaporphyrin. The crystal structures of rhenium(I) complexes of diheteroporphyrins revealed that the Re-I ion binds to both the Se/S atoms and one of the N atoms of the porphyrin core along with three terminal carbonyl groups in an octahedral fashion. The rhenium(I) complexes of 21,23-diheteroporphyrins are stabilized by a large counterion, the trichloro-bridged dirhenium(I) ion. We also present a detailed account of the spectral and redox properties of rhenium(I) tricarbonyl complexes of 21,23-diheteroporphyrins.

International audience; Characterization of acidic peptides and proteins is greatly hindered due to lack of suitable analytical techniques. Here we present the implementation of 213 nm ultraviolet photodissociation (UVPD) in high-resolution quadrupole-Orbitrap mass spectrometer in negative polarity for peptide anions. Radical-driven backbone fragmentation provides 22 distinctive fragment ion types, achieving the complete sequence coverage for all reported peptides. Hydrogen-deficient radical anion not only promotes the cleavage of Cα–C bond but also stimulates the breaking of N–Cα and C–N bonds. Radical-directed loss of small molecules and specific side chain of amino acids are detected in these experiments. Radical containing side chain of amino acids (Tyr, Ser, Thr, and Asp) may possibly support the N–Cα backbone fragmentation. Proline comprising peptides exhibit the unusual fragment ions similar to reported earlier. Interestingly, basic amino acids such as Arg and Lys also stimulated the formation of abundant b and y ions of the related peptide anions. Loss of hydrogen atom from the charge-reduced radical anion and fragment ions are rationalized by time-dependent density functional theory (TDDFT) calculation, locating the potential energy surface (PES) of ππ* and repulsive πσ* excited states of a model amide system.

Reaction of the tris(3-phenylpyrazolyl)methane sulfonate species (Tpms Ph )Li with the copper(I) complex [Cu(MeCN) 4 ][PF 6 ] affords [Cu(Tpms Ph )(MeCN)] 1 . The latter, upon reaction with equimolar amounts of cyclohexyl- (CyNC) or 2,6-dimethylphenyl (XylNC) isocyanides, or excess CO, furnishes the corresponding Cu(I) complexes [Cu(Tpms Ph )(CNR)] (R = Cy 2 , Xyl 3 ) or [Cu(Tpms Ph )(CO)] 4 . The ligated isocyanide in 2 or 3 (or the acetonitrile ligand in 1 ) is displaced by 3-iminoisoindolin-1-one to afford 5 , the first copper(I) complex containing an 3-iminoisoindolin-1-one ligand. The ligated acetonitrile in 1 undergoes nucleophilic attack by methylamine to give the amidine complex [Cu(Tpms Ph ){MeC(NH)NHMe}] 6 , whereas only the starting materials were recovered from the attempted corresponding reactions of 2 and 3 with methylamine. Complexes 1 or 6 form the trinuclear hydroxo-copper(II) species [(μ-Cu){Cu(μ-OH) 2 (Tpms Ph )} 2 ] 7 upon air oxidation in moist methanol. In all the complexes the scorpionate ligand facially caps the metal in the N , N , O -coordination mode.

International audience; There is an amazing diversity of cell wall composition and cell wall polysaccharide structure in wheat grain that is only partly explained by the complexity of plant tissues and cell type functions present in this organ. This review presents the state of the art on the structure and diversity of cell wall polymers in mature wheat grain and recent knowledge on cell wall metabolism with a focus on development-associated changes in wheat grain cell wall polysaccharides and genes controlling their biosynthesis. The diversity of polysaccharide structure observed in endosperm cell walls is tentatively explained on the basis of polysaccharide properties and cell type function. (c) 2012 Elsevier Ltd. All rights reserved.

The reactivity of bulky tris(trimethylsilyl) methyl group substituted aluminum trialkyl [(Me(3)Si)(3)CAlMe(2)center dot THF] (1) with a series of substituted benzoic acid derivatives has been investigated. An equimolar reaction of 4-methyl benzoic acid or 4-tert-butyl benzoic acid with 1 in toluene at 50 degrees C leads to the formation of cyclic dimeric aluminum carboxylates [(Me(3)Si)(3)CAl(Me)(mu-O(2)CC(6)H(4)R)](2) (R = Me 2; (t)Bu 3). Reaction of 3,5-di-iso- propylsalicylic acid (H(2)dipsa) with 1 leads to the exclusive isolation of a trimeric organoaluminum carboxylate [(Me(3)Si)(3)CAl(mu-ipsa)](3) (4), in which each aluminum is bound to two carboxylates, a phenoxide, and an alkyl group and produce a 12-membered macrocycle. Deliberate, but controlled, introduction of water in the form of 3,5-di-tert-butyl salicylic acid monohydrate (H(2)dtbsa center dot H(2)O) in the reaction with 1 in toluene leads to the isolation of carboxylate [(Me(3)Si)(3)CAl(mu-O)(mu-Hdtbsa)}(2)] (5) with a bicyclic structure. Compound 5 represents a rare example of an organoalumoxane carboxylate that simultaneously possesses alkyl, oxo, and carboxylate moieties on aluminum. (C) 2011 Elsevier B.V. All rights reserved.

International audience; The exposure of a carbonaceous siltstone sample to atmospheric entry, as part of the STONE 6 artificial meteorite experiment, has allowed a controlled investigation of the effect of heat shock during atmospheric entry on organic matter in carbonaceous meteorites and, potentially, sedimentary martian meteorites containing carbonaceous biomolecules. Thermal alteration is evident in an increase in structural order of the carbon (i.e. degree of graphitisation), preferential loss of thermally unstable compounds and substantial loss of extractable organic matter. There is a gradient of increasing alteration towards the outer, exposed margin of the rock, and also an increase in hydrocarbons that suggests outward migration following thermally-induced generation. The carbon has not been completely graphitised, and sufficient biomarker compounds survive to prove the biological origin of the organic matter. The experiment implies that meteorites of appropriate size could preserve evidence of biological activity on their parent body.

Pd(II) complexes of various donor atom ligands posses anti-tumor and anti-viral. -malarial, -fungal and -microbial activities. This review focuses on such properties of Pd(II) complexes and makes comparisons with similar properties of other metals. In the first part, the anti-viral, anti-fungal and anti-microbial activities of new I'd(H) complexes are described, classified according to the ligands used, namely; sulfur donors, ligands used as drugs, Schiff bases ligands and miscellaneous. The second part describes the anti-tumor properties of new Pd(II) complexes, similarly classified with sulfur and nitrogen and other donor ligands. The results are summarized in 1st and 2nd tables in this article which also contain all Pd(II) complexes described in Ref. [A. Garoufis. S.K. Hadjikakou, N. Hadjiliadis, in: M. Gielen, E.R.T. Tiekink (Eds.), Metals in Medicine, Palladium (Pd), in Metallotherapeutic Drugs and Metal-based Diagnostic Agents: The Use of Metals in Medicine, John Wiley & Sons, Ltd., 2005, p. 399 (Chapter 21)1 for comparison and clearly demonstrate the anti-tumor, anti-fungal, -viral, -microbial properties of several of them, as compared to those of other metals and especially to those of cisplatin. These promising results are encouraging further research in this field, for future applications. (C) 2008 Elsevier B.V. All rights reserved. Coordination Chemistry Reviews

Yilmaz, Veysel/0000-0002-2849-3332 WOS: 000255721000026 [Ag(mu-sac)(mu-ppz)](n), 1 and [Ag(mu-sac)(mu-bheppz)](n), 2 (sac = saccharinate, ppz = piperazine and bheppz = N,N'-bis(2-hydroxyethyl)piperazine) have been synthesized and characterized by elemental analyses, FT-IR, TGA/DTA and X-ray diffraction. Both complexes crystallize in the triclinic P (1) over bar space group and consist of one-dimensional coordination polymers. The silver(I) coordination environments in 1 and 2 are distorted T-shaped and tetrahedral, respectively. Silver(I) ions are doubly bridged by sac ligands, and further connected by ppz or bheppz bridges into linear infinite chains. The sac shows bidentate bridging mode, involving N- and carbonyl O-atoms in 1, while N- and sulfonyl O-atoms in 2. The polymeric chains are assembled into two-dimensional networks by hydrogen bonds and aromatic pi(sac)-pi(sac) stacking interactions. IR spectra and thermal analysis data are in agreement with the crystal structure. (C) 2008 Elsevier Ltd. All rights reserved.

While the phenolic oximes (R-saoH(2)) are well known for producing monometallic complexes of the type [MII(R-saoH)(2)] with Cu-II ions in near quantitative yield, their derivatisation opens the door to much more varied and interesting coordination chemistry. Here we show that combining the complimentary diethanolamine and phenolic oxime moieties into one organic framework (H4L1 and H4L2) allows for the preparation and isolation of an unusual family of [Cu-II](n) wheels, including saddle-shaped, single-stranded [Cu-8(II)] wheels of general formula [Cu-8(HL1)(4)(X)(4)] n[Y] (when n = 0, X = Cl-, NO3-, AcO-, N-3(-); when n = 2+X = (OAc)(2)/(2,2'-bpy)(2) and Y = [BF4](2)) and [Cu-8(HL2)(4)(X)(4)](X = Cl-, Br-), a rectangular [Cu-6(HL1)(4)] wheel, and a heterometallic [Cu4Na2(HL1)2(H2L1)(2)] hexagon. Magnetic studies show very strong antiferromagnetic exchange between neighbouring metal ions, leading to diamagnetic ground states in all cases. DFT studies reveal that the magnitude of the exchange constants are correlated to the Cu-N-O-Cu dihedral angles, which in turn are correlated to the planarity/puckering of the [Cu-II](n) rings.

Aminopyridinato-ligand-stabilized organoyttrium cations are accessible in very good yield through alkane elimination from trialkyl yttrium complexes with sterically demanding aminopyridines, followed by abstraction of one of the two alkyl functions using ammonium borates. At 80 degrees C and in the presence of small amounts of aluminum alkyl compounds, very high ethylene polymerization activities are observed if very bulky aminopyridinato ligands are used. During these polymerizations a reversible polyethylene chain transfer is observed between the organoyttrium cations and aluminum alkyls. The chain-transfer catalyst system described here is able to produce relatively long-chain (up to 4000 g mol-1) Al-terminated polyethylene with a molecular-weight distribution

Synthesis, structure, and catalysis studies of two Au- and Ag-based initiators, namely, [3-(N-tert-butylacetamido)-1-(2-hydroxycyclohexyl)imidazol-2-ylidene]AuCl (1c) and [3-(N-tert-butylacetamido)-1-(2-hydroxycyclohexyl)imidazol-2-ylidene]AgCl (1b), for the bulk ring-opening polymerization Of L-lactide are reported. Specifically, gold complex 1c was obtained from silver complex 1b by the transmetalation reaction with (SMe(2))AuCl. Silver complex 1b was synthesized by the treatment of 3-(N-tert-butylacetamido)-1-(2-hydroxycyclohexyl)imidazolium chloride (1a) with Ag(2)O, Compound la was synthesized directly from the reaction of N-tert-butyl-2-chloroacetamide, cyclohexene oxide, and imidazole. The molecular structures of 1a, 1b, and 1c have been determined by X-ray diffraction studies. The formation of neutral monomeric complexes with linear geometries at the metal centers was observed for both 1b and 1c. The An and Ag complexes 1c and 1b successfully catalyzed the bulk ring-opening polymerization of L-lactide at elevated temperatures under solvent-free melt conditions to produce moderate to low molecular weight polylactide polymers with narrow molecular weight distributions. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).

Bioactive peptides play critical roles in regulating most biological processes in animals. The elucidation of the amino acid sequence of these regulatory peptides is crucial for our understanding of animal physiology. Most of the (neuro)peptides currently known were identified by purification and subsequent amino acid sequencing. With the entire genome sequence of some animals now available, it has become possible to predict novel putative peptides. In this way, BLAST (Basic Local Alignment Searching Tool) analysis of the Drosophila melanogaster genome has allowed annotation of 36 secretory peptide genes so far. Peptide precursor genes are, however, poorly predicted by this algorithm, thus prompting an alternative approach described here. With the described searching program we scanned the Drosophila genome for predicted proteins with the structural hallmarks of neuropeptide precursors. As a result, 76 additional putative secretory peptide genes were predicted in addition to the 43 annotated ones. These putative (neuro)peptide genes contain conserved motifs reminiscent of known neuropeptides from other animal species. Peptides that display sequence similarities to the mammalian vasopressin, atrial natriuretic peptide, and prolactin precursors and the invertebrate peptides orcokinin, prothoracicotropic hormones, trypsin modulating oostatic factor, and Drosophila immune induced peptides (DIMs) among others were discovered. Our data hence provide further evidence that many neuropeptide genes were already present in the ancestor of Protostomia and Deuterostomia prior to their divergence. This bioinformatic study opens perspectives for the genome-wide analysis of peptide genes in other eukaryotic model organisms.

The condensation of bis(o-formylphenyl) selenide with 1,2-diaminoethane or 1,3-diaminopropane yielded the new macrocyclic ligands 1 and 2 in very good yields. Crystals of 1 are monoclinic, space group P2(1)/c with a = 10.0648(10) angstrom, b = 37.390(4) angstrom, c = 8.0073(11) angstrom, Z = 4 and those of 2 are triclinic, space group P (1) over bar with a 7.200(3), b = 9.137(3), C = 12.780(6) angstrom, Z = 1. The coordination chemistry of 1 and 2 has been studied with the "soft" metal ion Pd-II and "hard" metal ions Ni-II and Co-II. Reaction of [PdCl2(COD)] with 1 mol-equiv. of 1 or 2 in refluxing methanol and addition of NH4PF6 afforded the PdII complexes 5 and 6, respectively. Compound 5 is an unexpected partially hydrolyzed complex. It crystallizes in the tetragonal space group P4(1)2(1)2 with a = 10.7737(10) angstrom, b = 10.7737(10) angstrom, c = 28.190(5) angstrom, Z = 4. The structure shows the Pd-II ion coordinated to a square-planar arrangement of two selenium and two nitrogen atoms. Reaction of NiCl(2)(.)6H(2)O with I or 2 and NH4PF6 yielded complexes 7 and 8, respectively. The assignment of octahedral geometries to [Ni(L)](PF6)(2)] (7: L = 1; 8: L = 2) follows from their paramagnetism [mu(eff) = 3.23 (7), 1.81 (8) B.M.] and their UV/Vis spectra. This was also confirmed by single-crystal Xray studies. The crystal structures of 7 and 8 showed a distorted octahedral nickel center coordinated by two selenium and four nitrogen atoms. 7: Monoclinic, space group P21/c; a 9.979(2) angstrom, b = 18.901(4) angstrom, c = 19.333(4) angstrom; Z = 4. 8:Orthorhombic, space group Pna2(1); a = 20.277(5), b = 20.865(5), c = 9.416(2) angstrom; Z = 4. The cyclic voltammograms of 7 and 8 in MeCN solution show well-behaved quasi-reversible Ni-III/Ni-II couples. The analogous Co-II complex, [Co(1)](PF6)(2)] (9) also shows a quasi-reversible Co-III/Co-II couple. (c) Wiley-VCH Verlag GmbH T Co. KGaA, 69451 Weinheim, Germany, 2005.

The phosphido-substituted triruthenium cluster Ru(3)(CO)(9)(mu-H)(micro-PPh(2)) is shown to react with H(2) to form the trihydride cluster Ru(3)(CO)(9)(H)(mu-H)(2)(mu-PPh(2)), which undergoes a number of re-arrangement reactions on heating to yield other phosphido-substituted triruthenium clusters. In the presence of alkyne substrates, heating the system leads to catalytic hydrogenation via CO loss and the formation of a Ru(3)(eta(2)-PhC[double bond, length as m-dash]CHPh)(CO)(8)(micro-H)(PHPh(2)) resting state, in a reaction affected by the polarity of the solvent. No mononuclear fragments are observed in the catalytic transformation, confirming directly that the phosphido ligand is able to exert a stabilising influence on the cluster core.

The incompletely condensed silsesquioxane disilanol (c-C5H9)(7)Si7O9(OH)(2)OSiMePh2 has been used as a backbone for the synthesis of the diphosphinite ligand (C-C5H9)(7)Si7O9(OPPh2)(2)-OSiMePh2 (1), based on a silsesquioxane framework. By reaction with black selenium, the corresponding selenide (2) was obtained, showing a J(Se-P) value of 815 Hz in the P-31 NMR spectrum. DFT calculations established a good insight into the electron density of the P atoms present in the two model compounds CH3OPPh2 (3) and Ph2P(HSiOH)(2)OPH2 (4). The Mulliken charge distributions show a clear electron-withdrawing effect of the siloxy group, which is also present in diphosphinite ligand 1. By reaction of compound 1 with PdCl2-(C6H5CN)(2), the palladium complex [PdCl2R(OPPh2)(2)] (5) was obtained (R = (C-C5H9)(7)Si7O9-OSiMePh2). From a similar reaction of 1 with PtCl2(cod), the platinum analogue [PtCl2R(OPPh2)(2)] (6) could be isolated. The equimolar reaction Of Mo(CO)(4)(pip)(2) (pip = piperidine) with 1 yielded the molybdenum complex [Mo(CO)(4)R(OPPh2)(2)] (7). Ligand 1 showed a clear tendency to coordinate in a cis fashion for all complexes 5-7, as was determined by NMR spectroscopy and X-ray crystallography. However, the analogous reaction of 1 with RhCl(CO)(2) dimer yielded the mononuclear trans-[RhCl(CO)(1)] (8). Complexes 5-8 have been structurally characterized as the first examples of transition-metal complexes with a silsesquioxane-based bidentate phosphinite ligand.

Dietary fibers are at the forefront of nutritional research because they positively contribute to human health. Much of our processed foods contain, however, only small quantities of dietary fiber, because their addition often negatively affects the taste, texture, and mouth feel. There is thus an urge for novel types of dietary fibers that do not cause unwanted sensory effects when applied as ingredient, while still positively contributing to the health of consumers. Here, we report the generation and characterization of a novel type of soluble dietary fiber with prebiotic properties, derived from starch via enzymatic modification, yielding isomalto/malto-polysaccharides (IMMPs), which consist of linear (α1 → 6)-glucan chains attached to the nonreducing ends of starch fragments. The applied Lactobacillus reuteri 121 GTFB 4,6-α-glucanotransferase enzyme synthesizes these molecules by transferring the nonreducing glucose moiety of an (α1 → 4)-glucan chain to the nonreducing end of another (α1 → 4)-α-glucan chain, forming an (α1 → 6)-glycosidic linkage. Once elongated in this way, the molecule becomes a better acceptor substrate and is then further elongated with (α1 → 6)-linked glucose residues in a linear way. Comparison of 30 starches, maltodextrins, and α-glucans of various botanical sources, demonstrated that substrates with long and linear (α1 → 4)-glucan chains deliver products with the highest percentage of (α1 → 6) linkages, up to 92%. In vitro experiments, serving as model of the digestive power of the gastrointestinal tract, revealed that the IMMPs, or more precisely the IMMP fraction rich in (α1 → 6) linkages, will largely pass the small intestine undigested and therefore end up in the large intestine. IMMPs are a novel type of dietary fiber that may have health promoting activity.

Highly conserved glycoside hydrolase family 70 glucansucrases are able to catalyze the synthesis of α-glucans with different structure from sucrose. The structural determinants of glucansucrase specificity have remained unclear. Residue Leu(940) in domain B of GTF180, the glucansucrase of the probiotic bacterium Lactobacillus reuteri 180, was shown to vary in different glucansucrases and is close to the +1 glucosyl unit in the crystal structure of GTF180-ΔN in complex with maltose. Herein, we show that mutations in Leu(940) of wild-type GTF180-ΔN all caused an increased percentage of (α1→6) linkages and a decreased percentage of (α1→3) linkages in the products. α-Glucans with potential different physicochemical properties (containing 67-100% of (α1→6) linkages) were produced by GTF180 and its Leu(940) mutants. Mutant L940W was unable to form (α1→3) linkages and synthesized a smaller and linear glucan polysaccharide with only (α1→6) linkages. Docking studies revealed that the introduction of the large aromatic amino acid residue tryptophan at position 940 partially blocked the binding groove, preventing the isomalto-oligosaccharide acceptor to bind in an favorable orientation for the formation of (α1→3) linkages. Our data showed that the reaction specificity of GTF180 mutant was shifted either to increased polysaccharide synthesis (L940A, L940S, L940E, and L940F) or increased oligosaccharide synthesis (L940W). The L940W mutant is capable of producing a large amount of isomalto-oligosaccharides using released glucose from sucrose as acceptors. Thus, residue Leu(940) in domain B is crucial for linkage and reaction specificity of GTF180. This study provides clear and novel insights into the structure-function relationships of glucansucrase enzymes.

Bisamino(diphosphonite), p-C6H4{N{P(OC6H4C3H5-o)(2)}(2)}(2) (1), was prepared by reacting p-C6H4{N(PCl2)(2)}(2) with four equivalents of o-allylphenol in 85% yield. Compound 1 on treatment with [M(CO)(4)(HNC5H10)(2)] (M = Mo or W) gave cis-[{M(CO)(4)}(2){p-C6H4{N(P(OC6H4C3H5-o)(2))(2)}(2)}] (2, M = Mo; 3, M = W). The reaction of 1 with [Fe(eta(5)-C5H5)(CO)(2)](2) yielded the complex [{Fe(eta(5)-C5H5)(mu-CO)}(2){p-C6H4{N(P-(OC6H4C3H5-o)(2))(2)}(2)}] (4). Treatment of 1 with Fe(CO)(5) furnished a mononuclear complex, [{Fe(CO)(3)}(2)-{p-C6H4{N{P(OC6H4C3H5-o)(2)}(2)}(2)}] (5). The ruthenium(II) complex, [{(eta(6)-p-cymene)Ru(mu-Cl)(3)RuCl}(2){p-C6H4-{N(P(OC6H4C3H5-o)(2))(2)}(2)}] (6), was obtained on treatment of ligand 1 with [(eta(6)-p-cymene)Ru(Cl)(2)](2). The reaction between 1 and [Rh(COD) Cl](2) (COD = 1,5-cyclooctadiene) in dichloromethane resulted in the formation of a dinuclear complex [{RhCl}(2){p-C6H4{N(P(OC6H4C3H5-o)(2))(2)}(2)}] (7), in which the allyl double bond of one of the phenoxy groups coordinates to the metal center. When ligand 1 was reacted with two equivalents of [Pd(COD)Cl-2], a dinuclear complex [{PdCl2}(2)-{p-C6H4{N(P(OC6H4C3H5-o)(2))(2)}(2)}] (8) was obtained. With copper(I) halides, ligand 1 afforded tetranuclear complexes, [{(Cu(mu-X)(NCCH3))(2)}(2)-{p-C6H4{N(P(OC6H4C3H5-o)(2))(2)}(2)}] (9, X = Cl; 10, X = Br; 11, X = I). Reaction of 1 with four equivalents of [AuCl(SMe2)] produced a tetranuclear complex, [(AuCl)(4){p-C6H4{N{P(OC6H4C3H5-o)(2)}(2)}(2)}] (12). Complex 8 shows excellent catalytic activity in the Suzuki-Miyaura cross-coupling reaction under microwave conditions and complex 7 catalyzes hydroformylation of styrenes with good TONs.

The photolytic reaction of (Z)-1-ferrocenyltelluro-1-ferrocenyl-4-ferrocenyl-1-buten-3-yne with iron pentacarbonyl in hexane gives the tellurium coordinated carbonyl vinylallyl dinuclear iron complex 1, tellurium coordinated vinylallyl trinuclear iron complex 2, a lactone fused ferracyclopentadiene complex 3, and a butterfly complex 4. On reaction with PPh3, 1 undergoes fragmentation to yield a cyclopentadienone (7) and the starting material (Z)-1-ferrocenyltelluro-1-ferrocenyl-4-ferrocenyl-1-buten-3-yne. In addition, reactions of the tellurium ene-yne ligand with [ M(CO)(5)(THF)] or [ M(CO)(6)] give the M(CO)(5) adducts 8-10. All compounds have been characterized by IR, H-1 NMR and C-13 NMR spectroscopy and structures of 1-4 and 7 have been established by single crystal X-ray diffraction.

New rhenium(VII or III) complexes [ReO3(PTA)2][ReO4] (1) (PTA = 1,3,5-triaza-7-phosphaadamantane), [ReO3(mPTA)][ReO4]I (2) (mPTA = N-methyl-1,3,5-triaza-7-phosphaadamantane cation), [ReO3(HMT)2][ReO4] (3) (HMT = hexamethylenetetramine), [ReO3(η(2)-Tpm)(PTA)][ReO4] (4) [Tpm = hydrotris(pyrazol-1-yl)methane, HC(pz)3, pz = pyrazolyl], [ReO3(Hpz)(HMT)][ReO4] (5) (Hpz = pyrazole), [ReO(Tpms)(HMT)] (6) [Tpms = tris(pyrazol-1-yl)methanesulfonate, O3SC(pz)3(-)] and [ReCl2{N2C(O)Ph}(PTA)3] (7) have been prepared from the Re(VII) oxide Re2O7 (1-6) or, in the case of 7, by ligand exchange from the benzoyldiazenido complex [ReCl2{N2C(O)Ph}(Hpz)(PPh3)2], and characterized by IR and NMR spectroscopies, elemental analysis and electrochemical properties. Theoretical calculations at the density functional theory (DFT) level of theory indicated that the coordination of PTA to both Re(III) and Re(VII) centers by the P atom is preferable compared to the coordination by the N atom. This is interpreted in terms of the Re-PTA bond energy and hard-soft acid-base theory. The oxo-rhenium complexes 1-6 act as selective catalysts for the Baeyer-Villiger oxidation of cyclic and linear ketones (e.g., 2-methylcyclohexanone, 2-methylcyclopentanone, cyclohexanone, cyclopentanone, cyclobutanone, and 3,3-dimethyl-2-butanone or pinacolone) to the corresponding lactones or esters, in the presence of aqueous H2O2. The effects of a variety of factors are studied toward the optimization of the process.

Enhydra fluctuans leaves are traditionally sold on Indian markets for various health benefits. However, no phytochemical study on its high molecular weight compound has so far been performed. Chemical, chromatographic, ESI-TOF-MS, and NMR analyses of the water extracted carbohydrate polymer (CP) of E. fluctuans leaves showed the presence of a 24 kDa arabinogalactan having a (1,3)-linked beta-D-Galp main chain, substituted at O-6 by (1,6)-linked beta-D-Galp side chains. The latter residues were substituted at O-3 by (1,3)-, (1,5)-, and (1,3,5)-linked alpha-L-Araf chains, and nonreducing end-units of alpha-L-Araf and beta-D-Galp. This polymer contained esterified phenolic acids. Biochemical analysis revealed similarity in antioxidative potential between the identified carbohydrate polymer and known standard antioxidants. The highly branched side chains and the phenolic acid residues of the arabinogalactan might be the functional sites. Fluorimetric and ultraviolet spectrometric analyses showed that the studied carbohydrate polymer can form complex with bovine serum albumin having binding constant K = 2.42 x 10(6)/M and changes its microenvironment. Thus, traditional aqueous extraction method provides a carbohydrate polymer, which stimulates a fair biological response: this could represent an interesting approach in phytotherapeutic treatments.