Glutamic acid, structure and

Glutamic acid, structure and properties of, 1019 Glutamine, structure and properties of, 1018... 

The mechanism of interaction of amino acids at solid/ aqueous solution interfaces has been investigated through adsorption and electrokinetic measurements. Isotherms for the adsorption of glutamic acid, proline and lysine from aqueous solutions at the surface of rutile are quite different from those on hydroxyapatite. To delineate the role of the electrical double layer in adsorption behavior, electrophoretic mobilities were measured as a function of pH and amino acid concentrations. Mechanisms for interaction of these surfactants with rutile and hydroxyapatite are proposed, taking into consideration the structure of the amino acid ions, solution chemistry and the electrical aspects of adsorption. 

Prior to these structural studies, work using chemically modified proteins had shown the requirement for at least four histidine ligands per subunit together with a glutamic acid residue and Tyr-109 (Tyr-114 in met). The most recent X-ray work has eliminated the possibility that Tyr-109 is a ligand, a possibility proposed in earlier X-ray work. Other work on chemical modification of residues has been reviewed.1277... 

The 2.0 A electron density map of carboxypeptidase A shows three zinc-protein contacts (91). The ligands have been identified as histidine-69, glutamic acid-72 and histidine-196 (91, 101), where the numbers indicate the positions of the residues in the sequence counted from the N-terminal end. The geometry of the complex is irregular but resembles a distorted tetrahedron with an open position directed towards the active site pocket, and presumably occupied by water in the resting enzyme (91). The similarity with the tentative structure of the metal-binding site in carbonic anhydrase is striking. 

Bioactive macromolecules like peptides, proteins, and nucleic acids have been successfully embedded in planar LbL films. An important question is the retention of the bioactivity of the film-embedded biomolecules. The structural properties and stability of the LbL films formed from synthesized polypeptides of various amino acid sequences were recently reported [50]. The authors showed that control over the amino acid sequence enables control over non-covalent interpolypeptide interaction in the film, which determines the film properties. Haynie and coworkers showed by circular dichroism spectroscopy that the extent of adsorption of poly(L-glutamic acid) (PGA) and poly(L-lysine) (PLL) in the LbL films scales with the extent of secondary structure of the polypeptides in solution [51]. Boulmedais demonstrated that the secondary structure of the film composed of these polypeptides is the same as the peptide structure in the complex formed in solution [52], as found by Fourier transform IR spectroscopy (FUR). 

Problem 28.18 Glutathione, a powerful antioxidant that destroys harmful oxidizing agents in cells, is composed of glutamic acid, cysteine, and glycine, and has the following structure ... 

Perhaps the most striking evidence for the existence of helices in solution has been obtained from electron microscopy of poly-y-benzyl-L-glutamate and poly-L-glutamic acid (Hall and Doty, 1958). Micrographs of these polymers sprayed onto mica from solutions in which their helical properties are established, ethylene dichloride and water at pH 4.5, respectively, clearly show rods with diameters roughly those of a-helices and lengths of the same order as those expected for a-helices from molecular weight measurements in solution. The random coils of these polymers reveal no structure whatsoever upon similar visualization. 

Fig, 3,53 Chemical structures of glutamic acid, MSG, and selected related substances... 

The structure and spectra of /3-poly(L-glutamic acid) [ -(GluH) ] and its salts have been studied in some detail. X-Ray and electron-diffraction studies (Keith et al., 1969a,b), particularly on the Ca salt [)3-(GluCa) ], have indicated that this polypeptide forms an APPS structure. A model has been presented for the structure, and coordinates have been given for the atoms in the unit cell (Keith et al., 1969a), but a detailed test was not possible because of the paucity of diffraction data. 

Ohm TG, Muller H, Ulfig N, Braak E. 1990. Glutamic-acid-decarboxylase- and parvalbumin-like-immunoreactive structures in the olfactory bulb of the human adult. J Comp Neurol 291 1-8. 

The figure shows the steps catalyzed by glutamine synthase and the structural similarity between glutamic acid, MSO, and glufosinate. 

By acid hydrolysis with HCl, ten amino acids were obtained from the peat humic acids cystine, lysine, hystidine, arginine, aspartic acid, serine, glycine, glutamic acid, threonine and alanine. Proposals for the structure of humic acids have also been published of these, the structure of the humic acid according to Ludmila (1936) [51] is presented ... 

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