Conformational behavior of phenylglycines and hydroxyphenylglycines and non-planarity of phenyl rings.

The non-proteinogenic amino acids — phenylglycine (PG) and hydroxyphenylglycine (HPG) are crucial components of certain peptidic natural products and are important for the preparation of various medicines. In this, study, the conformation of model dipeptides Ac-X-NHMe of PG, p-HPG and 3, 5-di-hydroxyphenylglycine (3, 5-DHPG) was studied both in R and S form by quantum mechanical (QM) and molecular dynamics approaches. On the energy scale, the conformational states of these molecules in both the R and S were found to be degenerate by QM studies, stabilized by non-covalent interactions like carbonyl--carbonyl interactions, carbonyl-lp··π (aromatic ring) interactions etc. These interactions disappeared/weakened due to interaction of water molecules with carbonyl groups of backbone in simulation and water was found to interact with the aromatic ring through Ow-H··π or Owlp··π interactions. The degeneracy of conformational states was lifted in favor of R-form of PG and DHPG and water molecules interactions with aromatic ring led to non-planarity of the aromatic ring. In simulation studies, irrespective of the starting geometry, the , values for the R form correspond to inverse b/inverse collagen region and for the S-form, the , values correspond to b/collagen region i.e., adopt single conformation. The obtained results were in conformity with the CD spectroscopic data on D-PG and D-p-HPG. The conformational behavior of the unusual amino acids might be of great help in designing of bioactive peptides/peptide based drugs to be realized in single conformation – an essential requirement.

Effect of some organic additives on the corrosion behaviour of Cu-Fe and Cu-Al - Fe alloys in sulphuric acid solution

The effect of some organic compounds on the corrosion corr behavior of copper - iron alloy [1] and copper - aluminium - iron alloy [II] in 0.5 M H[2]SO[4] aqueous solution was investigated. The techniques of measurements were: weight loss, linear polarization and impedance spectroscopy. The organic compounds were: glycine [I], alanine [II], valine [III], histidine [IV], 2- aminothiazole [V] and 3- methyl -1- phenyl -2- pyrazolin -5- one [VI]. These compounds have high inhibition efficiency increases according to the order: I < II < III < IV < VI < V. The inhibitory effect of these compounds is achieved by their adsorption on the metallic surface via adsorption centers [N - atom and / or S- atom]. Their adsorption the metallic surface follows Temkins' isotherm of adsorption. The values of standard free energy of adsorption, delta G[degree sign] [ads], were calculated from the adsorption isotherms. The negative values of delta G[degree sign] [ads] indicate the adsorption process occurs spontaneously. There is an agreement between the results obtained from the different techniques of measurements

Molecular vibrations and normal modes in L-prolyl-glycyl-glycine using Wilson GF matrix method.

Collagen is one of the most important proteins containing mostly proline hydroxyproline and glycine. In collagen, approximately 33 percent of the amino acid residues are glycine and they occur at every third position, whereas remaining percentage is constituted by mainly proline or hydroxyproline and some part by alanine etc. having no definite positional placement in the chain. Thus, a study of conformation of proline and glycine containing dipeptides and tripeptides is important for understanding the conformation of collagen as a sequence of its constituent amino acids. In the present communication, we have studied spectral features of L-proline, L-prolyl-glycine (PG), L-prolyl-alanine (PA), L-glycylglycine (GG), Collagen and L-prolyl-glycyl-glycine (PGG). We have carried out detailed normal mode analysis of only PGG, because interpretation of spectra of other proline and glycine containing peptides can be treated as derivatives of this molecule. Urey-Bradley force field, which involves non-bonded interactions in the gem and cis configurations is used for calculation of normal modes. The "best-fit" set of constants are generated for PGG.

Extraction and carrier-facilitated transport of amino acids using synthetic non-cyclic receptors through bulk liquid membrane.

The extraction and carrier-facilitated transport of amino acids (leucine, valine and glycine) was studied through chloroform bulk liquid membrane system using a series of non-cyclic receptors such as diethylene glycol (1), diethylene glycol dimethyl ether (2), diethylene glycol dibutyl ether (3), diethylene glycol dibenzoate (4), triethylene glycol (5) and tetraethylene glycol (6). The amount of amino acid extracted and transported depends mainly upon the structure and the concentration of the receptors and also on the concentration of amino acid. The receptors 1 to 4, having small chain length and flexible end groups, formed stable complexes with amino acids, and the flexibility of receptors in different conformational forms was responsible for their carrier ability, while the receptors 5 and 6, having larger chain length showed poor carrier ability. Hydrophobicity of amino acids also play an important role in the extraction as well as transport process.

A Korean Family of Hypokalemic Periodic Paralysis with Mutation in a Voltage-gated Calcium Channel (R1239G)

Hypokalemic periodic paralysis (HOPP) is a rare disease characterized by reversible attacks of muscle weakness accompanied by episodic hypokalemia. Recent molecular work has revealed that the majority of familial HOPP is due to mutations in a skeletal muscle voltage-dependent calcium-channel: the dihydropyridine receptor. We report a 13-yr old boy with HOPP from a family in which 6 members are affected in three generations. Genetic examination identified a nucleotide 3705 C to G mutation in exon 30 of the calcium channel gene, CACNA1S. This mutation predicts a codon change from arginine to glycine at the amino acid position #1239 (R1239G). Among the three known mutations of the CACNA1S gene, the R1239G mutation was rarely reported. This boy and the other family members who did not respond to acetazolamide, showed a marked improvement of the paralytic symptoms after spironolactone treatment.

Characterization and biological activities of Chenopodium leaf hemagglutinin (CLH).

A hemagglutinin (CLH) having native molecular mass of 58 kDa and subunit molecular mass of 33 kDa had been purified from the leaves of Chenopodium amaranticolor. The protein agglutinated rabbit erythrocytes and no agglutination was observed with any of the groups A, B or O of human blood. The amino acid composition revealed that CLH was rich in aspartic acid, glutamic acid, glycine and phenylalanine and also significant amount of methionine. The N-terminal amino acid sequence analysis showed that CLH had no homology with any of the plant hemagglutinins studied so far. It was inactive towards human peripheral blood cells but mitogenic for mouse spleen B-lymphocytes. CLH inhibited protein synthesis in rat thymocytes at high concentration. CLH did not inhibit TMV infection of leaves indicating absence of antiviral properties.

Dielectric relaxation study of glycine and valine in water mixture using picosecond time domain reflectometry.

The complex permittivity of glycine and valine in water mixture for various temperatures and concentrations have been measured as a function of frequency between 10 MHz and 10 GHz using (TDR) time domain reflectometry technique. Dielectric parameters ie. static dielectric constant and relaxation time were obtained from the complex permittivity spectra using nonlinear least square fit method. From the values of relaxation time, thermodynamic parameters were determined.

Structural and conformational study of peptides containing glycine and alanine residues by 13C CPMAS NMR spectroscopy in solid state.

The results of the structural and conformational studies carried out using 13C CPMAS NMR technique on several glycine and alanine containing peptides in the solid state are reported. The study demonstrates the effects of variations in 13C chemical shifts due to conformation and hydrogen bonding. The possibility of applying this technique to obtain insight into the conformational characteristics of peptides of unknown structures is discussed.