Glutamic acid, organic structure

FIGURE 1.1 Structures of organic compounds referred to in the text (a) sucrose (also known as saccharose), (b) dimethyl sulfoxide (DMSO), (c) dimethylformamide (DMF), (d) sorbitol, (e) mannitol, (f) nitrilotriacetic acid (NTA), (g) citric acid, (h) N,N,N, N -fran,s-1,2-diaminocyclohexane-tetraacetic acid (CyTA), (i) saccharic acid, (j) glutamic acid. 

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. 

Freund and Lipton have shown that an Actinomycete, Nocardia as-teroides, has the same adjuvant action as Mycobacteria. The cell wall of this organism has a structure very similar to that of Mycobacteria—alanine, glutamic acid, a, -diaminopimelic acid, arabinose, mannose, and galactose being the principal components. White has shown that the wax D of Nocardia asteroidea is inactive as an adjuvant, whereas the delipidated cells are active. 

However, not only the kinetics but also the morphology of precipitated HAp nanocrystals will be modified by structure-mediated (epitaxial) adsorption of organic constituents such as poly(amino acids) at prominent lattice planes of HAp. For example, adsorption of poly(l-lysine) on (0 0 1) planes causes formation of polycrystalline nanocrystals of HAp whereas adsorption of poly(l-glutamic acid) leads to precipitation of large flat micron-sized single crystals of HAp (Stupp and Braun, 1997). Similar relations have been found in experiments involving adsorption of recombinant human-like collagen (Zhai and Cui, 2006) and bovine serum albumin (BSA) (Liu et al., 2003) on hydroxyapatite surfaces. 

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