Glutamic acid metal complexes

These examples illustrate that biomolecules may act as catalysts in soils to alter the structure of organic contaminants. The exact nature of the reaction may be modified by interaction of the biocatalyst with soil colloids. It is also possible that the catalytic reaction requires a specific mineral-biomolecule combination. Mortland (1984) demonstrated that py ridoxal-5 -phosphate (PLP) catalyzes glutamic acid deamination at 20 °C in the presence of copper-substituted smectite. The proposed pathway for deamination involved formation ofa Schiff base between PLP and glutamic acid, followed by complexation with Cu2+ on the clay surface. Substituted Cu2+ stabilized the Schiff base by chelation of the carboxylate, imine nitrogen, and the phenolic oxygen. In this case, catalysis required combination of the biomolecule with a specific metal-substituted clay. 

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. 

Each of the reactions is catalyzed by a different type of proteinoid or metal-proteinoid complex. The reaction of pyruvic acid to alanine and the reverse reaction are hypothesized from the experimental results in the amination of a-ketoglutaric acid 241 and the deamination of glutamic acid 2S). 

The complexation of the Group IIB metals by amino-acid and related derivatives continues to be a subject of interest stability constants reported include those for histidine and its derivatives, histamine, glycylhistamine, aspartic and glutamic acids, aspargine, glutamine, glycine, cysteine, and alanine. " ... 

Asymmetric induction using a transition metal complex (67), use of a carbohydrate template (68), and use of the chiral lactone 49 (69) or ester 50 (70) have all given effective syntheses of stereospecifically labeled samples of glycine. A further synthesis by Santaniello etal. (71, 72) has used glutamate decarboxylase to prepare labeled samples of y-aminobutyric acid 51 (Scheme 16). On cyclization, protection, and oxidation, these gave the labeled enamides 55, which were degraded to the labeled samples of glycine 23 (71, 72). 

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