Search

A nearly isosteric photosensitive amide-backbone substitution, which helps in the switching of the activities in the ribonuclease S complex is demonstrated. The complete abolishing of the enzymatic activity of the complex after its recovery from reisomerization proves that the thioxopeptide bond modified polypeptide backbone can be widely used in photoswitching of proteins.

A brief report on the photochemical studies of the photoelimination of a variety of carboxylate leaving groups from a series of N,N-diethyl alpha-keto amides is presented. Comparisons are made to an analogous series of N,N-diisopropyl alpha-keto amides.

Monolayers of newly synthesized amide phospholipids, 1-O-hexadecy-2-N-palmitoyl-2-amino-2-deoxy-sn-glycero-3-phosphocholine (L-ether-amide-PC) and 1-palmitoyl-2-N-palmitoyl-2-amino-2-deoxy-sn-glycero-3-phosphocholine (L-ether-amide-PC) were investigated at the air/subphase interface by Brewster angle microscopy combined with a conventional LB trough and Grazing incidence X-ray diffraction (GIXD).

The relationship between distorted intramolecular H-bonds and infrared absorption properties of the donor NH group in short helical peptides in solution are presented. The helical backbone in the peptides experiences distortions, the extent of which depends on the chain length, that are reflected in both the energy of the stretching mode and the molar extinction coefficient of the intramolecularity H-bonded N-H groups.

Propargylic boranes generated by lithiation of optically active N-proparglyoxazolidinones undergo reaction with a range of aldehydes to produce gamma,gamma-disubstituted allenamides with good diastereoselectivity. A new method for the diastereoselective synthesis of allenylcarbinols through propargylic boranes is developed.

The differences in RNA and DNA duplex geometry is sensed by the changed stereochemistry at 3' -amino function in the 5-atom thioacetamido linker of thioacetamido-linked nucleic acids and iso-thioacetamido-linked nucleic acids modified oligomers. The CD spectral differences for the dimer blocks are identical for those found in phosphodiester linked ribo/xylo dimers, but the 5-atom thioactamido linker has reversed the RNA binding selectivity to DNA binding selectivity by the change in configuration at the 3' -amino-substituted sugar.

The mid-infrared (IR) spectra of doubly protonated gramicidin S in the gas phase is measured for examining gramicidin S free of any influences of the environment. The differences between the values for the condensed phase are caused by interactions with the environment, as the condensed phase value is deduced for [beta]-sheet sections that are embedded in larger proteins, which have interacted with solvent or which are part of partially aggregated species.

Chimeric dyads based on dansyl and naphthalimide units linked through the polymethylene group are prepared and their photophysical and interactions with various metal ions are examined under different conditions. These dyads are unique as they form stable 2:1 stoichiometric complexes involving sulfonamide functionality and have acted as visual fluorescence ratiometric probes for the selective recognition of [Cu.sup.2+] ions.

The utility of multimode 2 dimensional (2D) infrared (IR) spectroscopy of the protein amide I' and II' vibrations for distinguishing protein secondary structure is described. 2D IR surfaces are used for parametrizing an excitonic model for the amide I'-II' manifold suitable to predict protein amide I'-II' spectra.

[super 1]H-detected and [super 13]C-detected protonless NMR experiments are combined to achieve full assignment of securin's backbone amide resonances. The results along with bioinformatic and biochemical data on the securin/separase interaction have helped in understanding the inhibitory action of securin on separase.

The synthesis and photophysical evaluations of two new fluorescent photoinduced electron-transfer (PET) anion sensors is described. These are based on 4-amino-1,8-naphthalimide fluorophores and diarylthiourea anion receptors connnected via a methylene spacer to the imide.

The process of femtosecond photolysis is employed to study the primary photodynamics of aqueous formamide. The majority of the formamide molecules are shown to convert the electronic excitation energy to vibrational excitation.

The hydration of simple formamide (F), N-methylformamide (NMF), N,N-dimethylformamide (DMF), acetamide (A), N-methylacetamide (NMA) and N,N'-dimethylacetamide (DMA) is analyzed in aqueous solutions by using Fourier transform infrared (FTIR) spectra of HDO isotopically diluted in [H.sub.2]O. The increased stability of the hydration sphere of NMA relative to DMA and of NMF relative to DMF has its origin in different geometries and also the stability of water cages containing the amides.

The thioenols derived from cyanomonothiocarbonylmalonamides and a cyanodithiocarbonylmalonamide are very reactive species and they have reacted under various conditions. Radical mechanisms, nucleophilic substitutions and condensations are some of the mechanisms used for these reactions.

The infrared spectroscopy is studied in the N-H region of gas-phase Ac-Phe-[(Ala).sub.5]-Lys-[H.sup.+] and Ac-Phe-[(ALA).sub.10]-Lys-[H.sup.+] in order to determine the spectroscopic features associated with helical structures. The N-H stretches have appeared as primarily local-mode oscillations, thus enabling infrared spectroscopy to provide structural information at the level of a single bond.

The conformational study on N-acetyl-N'-methylamides of oxazolidine and thiazolidine residues is carried out by using ab initio HF and density functional theory methods with the self-consistent reaction field method in order to examine the effects of the replacement of the [C.sup.[gamma]][H.sub.2] group in the prolyl ring by oxygen or sulfur atoms. The cis populations and rotational barriers to the cis-trans isomerization for both Oxa and Thz dipeptides in chloroform and water are consistent with the experimental values.

The insertion of bicyclohexylcarbodiimide into the N-H bond of the heteroaryldiamido is reported. The results indicate that the reactivity behavior of the linked diamido ligand strongly depends on the nature of the bridge system.

A study uses the self-assembling properties of alkylamide-tethered hexaazatrinaphthylenes (HATNA) to demonstrate that structurally robust columnar stacks of n-type pi-conjugated molecules with tunable lengths can be obtained by utilizing post-polymerization techniques after forming the supramolecular self-assembly initially. These nanostructures can be easily transferred to the substrate surface to create desired patterns by microcontact printing.

Study is conducted to evaluate the anharmonic potential parameters of the amide modes in peptides. A second-order perturbative vibrational treatment is used to calculate the vibrational frequencies of mono-, di- and tripeptides in the fundamental, overtone, and combination regions.

The structural and energetic issues associated with the peculiar arrangements of amide bonds are examined through quantum calculations. The frame of radiating cis-amide bonds can be considered as defining a new kind of peptidic material, endowed with specific self-assembling properties.

A detailed description about the preparation of silver nanoparticles by reduction of silver ions with formamide in the absence and presence of stabilizers, such as poly(N-vinyl-2-pyrrolidone) and SiO(sub 2), is presented. Surface-modified particles show optical properties that are significantly different from those of the primary silver dispersion.

A 2D turn element is successfully designed for oligo-amide sequences. The length of the spacers between the catechol and amide moities plays an important role in the folding process.

The sensitivity of the amide III vibration which takes place due to the ultraviolet resonance Raman studies of peptide and protein secondary structure is explained. This sensitivity takes place because of the Ramachandran dihedral psi angle dependent coupling of the amide nitrogen-hydrogen motion.

Two-dimensional (2D) infrared and 2D Raman correlation spectra in the amide III region were generated from the concentration-dependent spectral variations of the beta-lactoglobulin (BLG) solutions to investigate band assignments in the region and to explore concentration-induced conformational changes in BLG. The 2D infrared-Raman heterospectral correlation analysis has provided new insights into the correlation between the infrared and Raman bands in the amide III region and has confirmed some band assignments.

The AMP, tyrosinamide, and argininamide aptamers are converted into sensors. The AMP and argininamide aptamers are structurally well characterized but the structure of the tyrosinamide aptamer is unknown nor can it be predicted using conventional folding algorithms.