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A structural and functional model of bacterial nitric oxide reductase (NOR) has been designed by introducing two glutamates (Glu) and three histidines (His) in sperm whale myoglobin. X-ray structural data indicate that the three His and one Glu (V68E) residues bind iron, mimicking the putative [Fe.sub.B] site in NOR, while the second Glu (I107E) interacts with a water molecule and forms a hydrogen bonding network in the designed protein. Unlike the first Glu (V68E), which Iowered the heme reduction potential by ~110 mV, the second Glu has little effect on the heme potential, suggesting that the negatively charged Glu has a different role in redox tuning. More importantly, introducing the second Glu resulted in a ~100% increase in NOR activity, suggesting the importance of a hydrogen bonding network in facilitating proton delivery during NOR reactivity. In addition, EPR and X-ray structural studies indicate that the designed protein binds iron, copper, or zinc in the [Fe.sub.B] site, each with different effects on the structures and NOR activities, suggesting that both redox activity and an intermediate five-coordinate heme-NO species are important for high NOR activity. The designed protein offers an excellent model for NOR and demonstrates the power of using designed proteins as a simpler and more well-defined system to address important chemical and biological issues. biomimetic models | heme-copper oxidase | metalloprotein | protein design | protein engineering doi/10.1073/pnas.1000526107

Abnormalities in repolarization and its rate dependence are known to related to increased proarrhythmic risk. A number of repolarization-related electrophysiological properties are commonly used as preclinical biomarkers of arrhythmic risk. However, the variability and complexity of repolarization mechanisms make the use of cellular biomarkers to predict arrhythmic risk preclinically challenging. Our goal is to investigate the role of ionic current properties and their variability in modulating cellular biomarkers of arrhythmic risk to improve risk stratification and identification in humans. A systematic investigation into the sensitivity of the main preclinical biomarkers of arrhythmic risk to changes in ionic current conductances and kinetics was performed using computer simulations. Four stimulation protocols were applied to the ten Tusscher and Panfilov human ventricular model to quantify the impact of [+ or -] 15 and [+ or -] 30% variations in key model parameters on action potential (AP) properties, [Ca.sup.2+] and [Na.sup.+] dynamics, and their rate dependence. Simulations show that, in humans, AP duration is moderately sensitive to changes in all repolarization current conductances and in L-type [Ca.sup.2+] current ([I.sub.CaL]) and slow component of the delayed rectifier current ([I.sub.Ks]) inactivation kinetics. AP triangulation, however, is strongly dependent only on inward rectifier [K.sup.+] current ([I.sub.KI]) and delayed rectifier current ([I.sub.Kr]) conductances. Furthermore, AP rate dependence (i.e., AP duration rate adaptation and restitution properties) and intracellular [Ca.sup.2+] and [Na.sup.+] levels are highly sensitive to both [I.sub.CaL] and [Na.sup.+]/[K.sup.+] pump current ([I.sub.NaK]) properties. This study provides quantitative insights into the sensitivity of preclinical biomarkers of arrhythmic risk to variations in ionic current properties in humans. The results show the importance of sensitivity analysis as a powerful method for the in-depth validation of mathematical models in cardiac electrophysiology. biological variability: arrhytbmia: computer simulation doi:10.1152/ajpheart.00263.2009

The regulation of metal ion transport within neurons is critical for normal brain function. Of particular importance is the regulation of redox metals such as iron (Fe), where excess levels can contribute to oxidative stress and protein aggregation, leading to neuronal death. The divalent metal transporter 1 (DMT1) plays a central role in the regulation of Fe as well as other metals; hence, failure of DMT1 regulation is linked to human brain pathology. However, it remains unclear how DMT1 is regulated in the brain. Here, we show that DMT1 is regulated by Ndfip1 (Nedd4 family-interacting protein 1), an adaptor protein that recruits E3 ligases to ubiquitinate target proteins. Using human neurons we show the Ndfip1 is upregulated and binds to DMT1 in response to Fe and cobalt (Co) exposure. This interaction results in the ubiquitination and degradation of DMT1, resulting in reduced metal entry. Induction of Ndfip1 expression protects neurons from metal toxicity, and removal of Ndfip1 by shRNAi results in hypersensitivity to metals. We identify Nedd4-2 as an E3 ligase recruited by Ndfip1 for the ubiquitination of DMT1 within human neurons. Comparison of brains from [Ndfip1.sup.-/-] with [Ndfip1.sup.+/+] mice exposed to Fe reveals that [Ndfip1.sup.-/-] brains accumulate Fe within neurons. Together, this evidence suggests a critical role for Ndfip1 in regulating metal transport in human neurons. cobalt | iron | Nedd4-2 | ubiquitin

Secondary transporters of citrate in complex with metal ions belong to the bacterial CitMHS family, about which little is known. The transport of metal-citrate complexes in Streptomyces coelicolor has been investigated. The best cofactor for citrate uptake in Streptomyces coelicolor is [Fe.sup.3+], but uptake was also noted for [Ca.sup.2+], [Pb.sup.2+], [Ba.sup.2+], and [Mn.sup.2+]. Uptake was not observed with the [Mg.sup.2+], [Ni.sup.2+], or [Co.sup.2+] cofactor. The transportation of iron-and calcium-citrate makes these systems unique among the CitMHS family members reported to date. No complementary uptake akin to that observed for the CitH ([Ca.sup.2+], Ba2+, Sr2+) and CitM ([Mg.sup.2+], [Ni.sup.2+], [Mn.sup.2+], [Co.sup.2+], [Zn.sup.2+]) systems of Bacillus subtilis was noted. Competitive experiments using EGTA confirmed that metal-citrate complex formation promoted citrate uptake. Uptake of free citrate was not observed. The open reading frame postulated as being responsible for the metal-citrate transport observed in Streptomyces coelicolor was cloned and overexpressed in Escherichia coli strains with the primary [Fe.sup.3+]-citrate transport system OrecABCDE) removed. Functional expression was successful, with uptake of [Ca.sup.2+]-citrate, [Fe.sup.3+]-citrate, and [Pb.sup.2+]-citrate observed. No free-citrate transport was observed in IPTG (isopropyl-13-D-thiogalactopyranoside)induced or -uninduced E. coli. Metabolism of the [Fe.sup.3+]-citrate and [Ca.sup.2+]-citrate complexes, but not the [Pb.sup.2]+-citrate complex, was observed. Rationalization is based on the difference in metal-complex coordination upon binding of the metal by citrate.

The effects of different concentration of MgS[O.sub.4]7[H.sub.2]O, Fe[Cl.sub.3]6[H.sub.2]O, ZnS[O.sub.4].7[H.sub.2] CuS[O.sub.4]5[H.sub.2]O and MnS[O.sub.4]5[H.sub.2]O on lipid and GLA production by Cunninghamella sp. 2A1 were studied in submerged culture fermentation. Cultivation was performed in 250 ml conical flask (100ml working volume), at 30[degrees]C and 250 rpm agitation for 120h. [Mg.sup.2+], [Fe.sup.2+] and [Zn.sup.2+] have significant effect on lipid accumulation as inclusion of each ions resulted in a 64, 43 and 33% increase in lipid content compared to cultures which was cultivated with the omission of each ions, respectively. All three metal ions also affected GLA production by Cunninghamella sp. 2A1 with [Zn.sup.2+] having the most profound effect with an increase of up to 74% of GLA yield (g GLA/g lipidless biomass) achieved. As omission of any single metal ions did not affect biomass concentration achieved, we concluded that metal ions components in production media may have affected lipid and GLA production by affecting pathways involved in the biosynthesis of lipid and GLA. This study reports the critical concentration of each metal ion for optimal lipid and GLA production by Cunninghamella sp. 2A1. Key words: Cunninghamella sp., lipid, GLA and metal ion, INTRODUCTION Microorganisms produce lipid for essential functioning of cell membranes and other membranous structures. However not all microbes are able to produce substantial amount of lipid. Those that produce more [...]

Protein and peptide assembly into amyloid has been implicated in functions that range from beneficial epigenetic controls to pathological etiologies. However, the exact structures of the assemblies that regulate biological activity remain poorly defined. We have previously used [Zn.sup.2+] to modulate the assembly kinetics and morphology of congeners of the amyloid [beta] peptide (A[beta]) associated with AIzheimer's disease. We now reveal a correlation among A[beta]-[Cu.sup.2+] coordination, peptide self-assembly, and neuronal viability. By using the central segment of A[beta], HHQKLVFFA or A[beta](13-21), which contains residues H13 and H14 implicated in A[beta]-metal ion binding, we show that [Cu.sup.2+] forms complexes with A[beta](13-21) and its K16A mutant and that the complexes, which do not selfassemble into fibrils, have structures similar to those found for the human prion protein, PrP. N-terminal acetylation and H14A substitution, Ac-A[beta](13-21)H14A, alters metal coordination, allowing [Cu.sup.2+] to accelerate assembly into neurotoxic fibrils. These results establish that the N-terminal region of A[beta] can access different metal-ion-coordination environments and that different complexes can lead to profound changes in A[beta] self-assembly kinetics, morphology, and toxicity. Related metal-ion coordination may be critical to the etiology of other neurodegenerative diseases. copper-binding | neurotoxicity | self-assembly

The role of sodium ion/potassium ion ATPase in controlling tight junction formation and function during early stages of embryonic development in mouse is studied.

Copper ions induce expression of the Bacillus subtilis copZA operon encoding a metallochaperone, CopZ, and a CPx-type ATPase efflux protein, CopA. The copZA promoter region contains an inverted repeat sequence similar to that recognized by the mercury-sensing MerR protein. To investigate the possible involvement of MerR homologues in copZA regulation, null mutations were engineered affecting each of four putative MerR-type regulators: yyaN, yraB, yfmP and yhdQ. Two of these genes affected copper regulation. Mutation of yhdQ (hereafter renamed cueR) dramatically reduced copper induction of copZA, and purified CueR bound with high affinity to the copZA promoter region. These results suggest that CueR is a direct regulator of copZA transcription that mediates copper induction. Surprisingly, a yfmP mutation also reduced copper induction of copZA. Sequence analysis suggested that yfmP was cotranscribed with yfmO, encoding a putative multidrug efflux protein. The yfmPO operon is autoregulated: a yfmP mutation derepressed the yfmP promoter and purified YfmP bound the yfmP promoter region, but not the copZA promoter region. Since the yfmP mutant strain was predicted to express elevated levels of the YfmO efflux pump, it was hypothesized that copper efflux might be responsible for the reduced copZA induction. Consistent with this model, in a yfmP yfmO double mutant copper induction of copZA was normal. The results demonstrate the direct regulation of the B. subtilis copper efflux system by CueR, and indirect regulation by a putative multidrug efflux system.

To study the periplasmic branch of iron (ferric ion) uptake systems in Gram-negative bacteria, genetic reconstitution experiments were initiated in Haemophilus influenzae involving exchange of the periplasmic iron-binding protein. The expression of many of the heterologous periplasmic ferric-binding proteins (FbpAs) was quite limited. Transformation experiments with the fbpA gene from Neisseria gonorrhoeae yielded two colony sizes with different phenotypic characteristics. The small colonies contained the intact N. gonorrhoeae fbpA gene and were deficient in utilization of transferrin iron. The large colonies contained hybrid H. influenzae/N, gonorrhoeae fbpA genes, were proficient in transferrin iron utilization and had enhanced levels of expression of FbpA. These hybrid genes included several that encoded the mature N. gonorrhoeae FbpA with the H. influenzae signal peptide. To more fully evaluate the effect of foreign signal peptides, a series of hybrid genes were prepared that exchanged the signal peptides from H. influenzae FbpA, N. gonorrhoeae FbpA and the TEM-1 [beta]-Iactamase. The presence of the H. influenzae leader was required for functional expression of FbpAs and was shown to dramatically increase the level of [beta]-lactamase activity.

The discovery of RNA catalysis provided a paradigm shift in biology, insight into the evolution of life on the planet and a challenge to understand its mechanistic origins. RNA has limited catalytic resources that must be used to maximal effect. Consequently, RNA catalysis tends to be multifactorial, with several processes contributing to an overall significant enhancement of reaction rate. These include general acid-base catalysis, electrostatic effects, and substrate orientation and proximity. The main players are the RNA nucleobases and bound metal ions. Although most ribozymes carry out phosphoryl transfer, the same considerations appear to apply to peptidyl transfer in the ribosome.

Motility on surfaces is an important mechanism for bacterial colonization of new environments. In this report, we describe detection of rapid surface motility in the wild-type Bacillus subtilis Marburg strain, but not in several B. subtilis 168 derivatives. Motility involved formation of rapidly spreading dendritic structures, followed by profuse surface colonies if sufficient potassium ion was present. Potassium ion stimulated surfactin secretion, and the role of surfactin in surface motility was confirmed by deletion of a surfactin synthase gene. Significantly, this motility was independent of flagella. These results demonstrate that wild-type B. subtilis strains can use both swimming and sliding-type mechanisms to move across surfaces.

Fungal laccase gene transcription is strongly induced by copper ions; notably, some laccase promoters contain multiple putative metal-responsive elements (MREs). Previously, it has been demonstrated that the Pleurotus ostreatus laccase genes poxc and poxa1b are transcriptionally induced by copper, and several putative MREs were found in the promoter regions of these genes, which extend for about 400 nt upstream of the start codon (ATG). Identification of MRE sequences, which are protected by protein binding in the poxc and poxa1b promoter regions, has been achieved by footprinting analyses. Electromobility shift assays led to the evaluation of the ability of the identified MREs to bind protein(s), and the role of specific nucleotides of these elements in complex formation has also been analysed. The formation of complexes between analysed MREs and fungal proteins requires the absence of metal ions. Proteins extracted from fungus grown in copper-depleted medium are able to form complexes with MREs, whilst proteins extracted from fungus grown in copper-containing medium are able to form complexes only in the presence of a metal chelator. Moreover, copper-depleted proteins are unable to form complexes when copper or zinc ions are added. UV-cross-linking analyses led to the determination of the molecular masses of the MRE-binding proteins. In the poxa1b promoter, a GC-rich region, homologous to the core binding site for transcription factor Sp1, decreases the binding affinity of the adjacent MRE, affecting its interactions with fungal protein factors.

The sense of smell is arguably our most primal faculty and also the least understood. Even our own olfactorily impaired species is capable of detecting [approximately equal to] 10,000 distinct scents [Buck, L. & Axel, R. (1991) Cell 65, 175-1871. To achieve that amazing diversity, mammals have [approximately equal to] 1,000 olfactory genes, which accounts for [approximately equal to] 3% of their entire genome [Mombaerts, P. (1999) Science 286, 707-711]. The olfactory receptors (ORs) are believed to be seven-helix transmembrane proteins, with an odorant-binding site on the periplasmic domain and a G protein-binding site on the cytoplasmic domain. Odorants first bind to an OR, which then undergoes some structural change that triggers the G protein activation and the following cascade of events leading to nerve cell activity. The structural details of ORs, however, remain to be determined. In this paper, we will describe a hypothesis in which metal ions play an important role for odorant recognition. We analyze the predicted structure and consensus sequence of the ORs and propose a metal-binding site in the loop between fourth and fifth helix (4-5 loop). We have prepared synthetically a pentapeptide that contains this putative binding site and find that it not only has high affinity for binding Cu(II) and Zn(II) ions, but that it also undergoes a dramatic transition to an [alpha]-helical structure upon metal ion binding. Based on these observations, we propose a 'shuttlecock' mechanism for the possible structural change in ORs upon odorant binding. This mechanism involves membrane penetration of the 4-5 loop after residue charge neutralization by metal ion binding. olfaction | G protein-coupled receptors | transmembrane protein

Research has been conducted on tristetraprolin Nup475, zinc-binding domains. The three-dimensional solution structure of one of the domains has been investigated via the use of multidimensional nuclear magnetic resonance spectroscopy, and the results reveal a fold around the central zinc ion.

Research has been conducted on metal ions Ca (super)2+ and Mn (super)2+ which are important for cofactor activity generation following factor VIII reconstitution from its isolated light and heavy chains. Results demonstrate that similar to Ca (super)2+, Mn (super)2+ has a high-affinity binding site for factor VIII which does not affect the affinity of heavy or light chains of factor VIII heterodimer.

Research has been conducted on metal ions. Results demonstrate that enzyme-DNA association rate depends on metal ions and that these ions are involved in DNA binding by P(nu)uII endonuclease.

Research has been conducted on Helicobacter pylori ability to adapt to the changing gastric environment. The study of regulatory responses to coper ions carried out via the use of RNA profiling has revealed that copper induces transcription of H. pylori genes and that copper resistence determinants CrdA (HP1326), CrdB (HP1327) are important for adaptation to copper-rich environmental conditions.

Research has been conducted on the nucleic acid quadruplexes. The characterization of the unimolecular quadruplexes' metal ion binding site has been carried out in frozen solution via the use of X-ray absorption fine structure measurements and the results are discussed.

Water-soluble luminescent CdS quantum dots (QDs) capped by polyphosphate, L-cysteine, and thioglycerol were synthesized in aqueous solution. The ligands were found to have a profound effect on the luminesence response of CdS QDs to physiologically important metal cations. Polyphosphate-capped CdS QDs were sensitive to nearly all mono- and divalent cations, showing no ion selectivity. Conversely, thioglycerol-capped CdS QDs were sensitive to only copper and iron ions. Similar concentrations of physiologically relevant cations, such as zinc, sodium, potassium, calcium, and magnesium ions did not affect the luminescence of thioglycerol-capped CdS QDs. On the other hand, L-cysteine-capped CdS QDs were sensitive to zinc ions and insensitive to other physiologically important cations, such as copper, calcium, and magnium ions. To demonstrate the detection capability of these new ion probes, L-cysteine and thioglycerolcapped CdS QDs were used to detect zinc and copper ions in physiological buffer samples. The detection limits were 0.8 [micro]M for zinc (II) and 0.1 [micro]M for copper (II) ions. The emission enhancement of the QDs by zinc (II) is attributed to activation of surface states, whereas the effective reduction of copper (II) to copper (I) may explain the emission decrease of the thioglycerol-capped CdS QDs when charged with copper ions. Unlike organic fluorescent dyes, the thioglycerol-capped luminescent CdS QDs discriminate between copper and zinc ions and are therefore suitable for the analysis of copper ions in biological samples in the presence of physiological concentrations of zinc ions. The interference of iron ions with zinc and copper ion detection is attributed to an inner filter effect, which is eliminated by adding fluoride ions to form the colorless complex Fe[F.sub.6.sup.3-]. To the best of our knowledge, this is first use of luminescent semiconductor quantum dots as selective ion probes in aqueous samples.

Raman spectroscopy is applied to an investigation of the interfacial chemistry of silica-immobilized 8-hydroxyquinoline (8HQ) for binding of metal ions over a wide range of solution conditions. Since the derivatized silica has a high specific binding capacity, the mass of silica equilibrated with solution needs to be small for studies of reactions with trace-level ([micro]M) metal ions; otherwise, the solution volume required to reach equilibrium becomes excessive. To address this problem, a small-volume flow cell is designed for this work using a fiber-optic Raman probe inserted directly into the packed end of a micro-column, allowing excitation and collection of Raman scattering from less than 10 mg of derivatized silica. This cell is attached to a flow system that allows control of solution conditions while the response of the 8HQ-silica material is acquired by continuous monitoring of Raman scattering from the sample. Raman spectra of the deprotonated, neutral, protonated, and copper-complexed forms of the ligand can be distinguished, allowing proton-transfer and metal ion binding reactions of the ligand to be investigated. To account for the effects of changing surface potential on these reactions, [xi]-potential measurements are made on the 8HQ-silica particles under the same solution conditions that are employed in the Raman scattering measurements. The observed pH dependence of metal ion binding was corrected for the effect of surface potential using the Boltzmann equation, and the resulting equilibrium constant for binding of [Cu.sup.2+] was independent of metal ion concentration over a 100-fold range from 30 [micro]M to 5 mM.

Research has been conducted on the anionic mixed rhodium-nickel carbonyl clusters. The relationships between these clusters and such group 13 analogues as polyhedral borane and metallaborane frameworks have been investigated and are discussed.

Research has been conducted on the mononuclear cis-dimethoxo octahedral Fe(III) complex with a singly deprotonated monoanionic ligand and the dinuclear mu-oxo trigonal bipyramidal Fe(III) complex with a doubly deprotonated dianionic ligand. The syntheses and characterization of these complexes are described.

Research has been conducted on the complexes formed from the transition metal ions V (super)3+, Sc (super)+ and Ti (super)2+. The results of the computations study of the binding in these complexes has been carried out and the results are reported.

Research has been conducted on the calix[4]azacrown ethers with the double bond conjugated indoaniline chromophore appended to the azacrown nitrogen atom. The synthesis of these ethers has been carried out and the details are described.

Research has been conducted on the TetA efflux pump protein. The study of the site where tetracyclin binds to this pump protein has been carried out and the results indicate that when chelated to tetracyclin Fe (super)2+ cleaves TetA backbone at glutamine 225 in transmembrane helix 7.

Research has been conducted on octahedral and tetrahedral solvated cobalt(II) complexes. The equilibrium enthalpy differences between these complexes have been obtained in primary alkylamines via the use of the spectrophotometric method and the details are reported.

Research has been conducted on the non-Kramers Ni (super)2+ ion from pseudotetrahedral nickel(II) complexes. The use of the high-frequency and high-field electron paramagnetic resonance spectroscopy in probing this ion is described.

Research has been conducted on the phenol-based compartment ligand with bidentate and tridentate arms. Results indicate that this ligand has afforded heterodinuclear M (sub)a (super)II M (sub)b (super)II complexes and that these complexes are isostructural with the heterodinuclear bridged core.

Research has been conducted on the fulleride anions. The preparation of these anions by means of deprotonation of fullerene C-H bonds and the alkylation of fullerene ions prepared electrochemically are described.

Research has been conducted on the flap endonuclease-1. The role of metal ions in the endonuclease-1-catalyzed chemical transition has been investigated via biophysical and biochemical experiments and via characterization of Mg (super)2+ effect on protein conformation, substrate binding and enzyme activities and the details are reported.

Research has been conducted on the H-N-H endonuclease motif within colicin E9. The transition metal binding to this motif has been investigated via the use of the stopped-flow fluorescence analysis and the results indicate that all tested transition metal ions bind via the multistep mechanisms.

Research has been conducted on the bacterial ribonuclease P RNA subunit. The role of the P protein in the magnesium ion interactions in Bacillus subtilis RNase P has been investigated and the results indicate that it interacts with the 5' leader sequence and enhances the pre-tRNA affinity.

Research has been conducted on the unphosphorylated Na (super)+, K (super)+ -ATPase. The kinetics of the conformational change of this ATPase has been investigated via the use of the stopped-flow technique and the results suggest that Na (super)+ ions play a regulatory role in enhancement of the conformational transition rate.

Research has been conducted on the molecular rectangle ions. The electron capacity of these ions has been investigated via cyclic voltammetry, EPR and UV-vis-near-IR spectroelectrochemistry in acetonitrile and dichloromethane and the details are included.

Research has been conducted on the hydrogen-bonded one-dimensional supramolecular array and a 3D network with a large tunnel. Results indicate the coordination of the crown ether moieties with the metal ions in both complexes.

Research has been conducted on the cyclic N-acyliminium ions. The gas-phase reactivity of these ion has been investigated in Mannich-type reactions with enol silane and the results are reported.

Research has been conducted on Trametes pubescens laccase isoenzyme LAP2. The purification and characterization of this laccase by the fungus T. pubescens has been carried out under the copper growth conditions and its regulation has been investigated and described.

It has long been recognized that the pathogenicity of a broad range of intracellular parasites depends on the availability of transition metal ions, especially iron. Nramp1 (natural resistance-associated macrophage protein 1), a proton-coupled divalent metal ion transporter, has been identified as a controlling factor in the resistance or susceptibility to infection with a diverse range of intracellular pathogens such as Toxoplasma, Salmonella, Mycobacterium, and Leishmania. The role of divalent metal ion transport is even more compelling given the existence of Nramp homologs in several intracellular parasites, such as mycobacteria. We have confirmed the functional homology of the Nramp homologue from Mycobacterium leprae by using a yeast complementation assay for divalent cation uptake. To facilitate a concerted biochemical and structural analysis of this important class of transporters, the M. leprae Nramp was expressed in Escherichia coli. Dual affinity tags were engineered at the N and C termini to allow for isolation of full-length protein at >95% purity. Site-directed spin labeling of Cys-299 reveals a flexible hinge-like domain. A weak dipolar interaction is detected between the nitroxide and paramagnetic transition ions, indicating this position is approximately 19 A from the nearest high affinity binding site.

Research has been conducted on the heteronuclear diethylcarbamato complexes. The preparation of these complexes from the isostructural homonuclear precursors carried out via the use of solvothermal methodology is described.

Research has been conducted on the copper(II) metal ion receptors. The preparation of the bifunctional ligands with the receptor sites which can bind these metal ions has been carried out and the results are described.

Research has been conducted on the divalent metal binding properties. The differences between the binding properties of type I and II methionyl aminopeptidase have been investigated via the analysis of the type II methionyl aminopeptidase from Pyrococcus furiosus's ability to bind divalent metal ions and the results are described.

The authors review the publications on rare-earth ions. The topics of interest include spin states of rare-earth ions and the nature of magnetic coupling which involves gadolinium(III).

The authors review the publications on electroluminescence of organic materials. The topics of interest include organic electroluminescent devices and lanthanide metal ion complexes as the emitting layer.

Results demonstrate that the ferric uptake repressor in Bacillus subtilis exists in several metallated forms that differ in DNA target selectivity and in sensitivity to hydrogen peroxide oxidation, suggesting that metal ion composition of the growth medium influences the PerR regulon genes' transcription.

Research has been conducted on the mono-, di- and trichloroarenes and aryltrimethylammonium sals. The photostimulated reactions of these salts with Me (sub)3 Sn (super)- ions have been carried out in liquid ammonia to produce stannanes and the details are reported.

Research has been conducted on the hydrogen-bonded complexes. The study of the Cu(II) complex dimers linked via O-H...O hydrogen bonds carried out via the use of the density functional calculations is presented.