Complexation copper glycine

A variety of other metals and their complexes have been studied for radioprotective activity. Among these are copper glycinate, strontium chloride, ZnNa -diethylenetriaminepentaacetate (ZnDTPA), and selenium, which has been studied because of its relationship to endogenous antioxidant mechanisms, especiaHy GSH peroxidase and vitamin E. 

Chelate is pronounced kee late and is derived from the Greek word for claw. The copper/glycine complexation reaction is shown below. 

The number of covalent bonds that a cation tends to form with electron donors is its coordination number. Typical values for coordination numbers are 2,4, and 6. The species formed as a result of coordination can be electrically positive, neutral, or negative. For example, copper(II), which has a coordination number of 4, forms a cationic ammine complex, Cu(NH3)4 a neutral complex with glycine, Cu(NH2CH2COO)2 and an anionic complex with chloride ion, CuClj. ... 

Several features of the above studies were reinvestigated in a detailed kinetic study of the copper(II) complexes of glycine methyl ester and phenylalanine ethyl ester in glycine buffer at pH 7.3 (26). Glycine was selected as a buffer in this study in order that a small increase in the glycine concentration caused by the hydrolysis reaction would not increase the concentration of copper(II) complexes to a significant extent. It was found that the rate constant for the hydrolysis of the copper(II) complex of DL-phenylalanine ethyl ester was 106 times greater than the rate constant obtained for the alkaline hydrolysis of the free ester (25). 

Copper complexes of amino acids have also been found to be effective in preventing and reducing the severity of Shay ulcers [267, 268]. As data in Table 6.17 show, the copper complex of glycine was the most effective of all of the amino-acid complexes studied and it was essentially as effective as Propantheline in reducing ulcer number as well as ulcer severity [267]. 

Copper is often found in biochemical systems, usually in peptides and proteins. Extensive reviews may be found (66, 106, 557). Semiquantita-tive discussion (112) of the significance of the results, which usually show that the copper environment has axial symmetry and with a distorted octahedral structure are numerous. The use of model compounds has been discussed by Malmstrom and Vanngard (477). In many cases there appears to be dimeric species present (9S). A system of importance which has been extensively studied is the series of complexes with glycine and triglycine (209, 638, 707, 712). The ESR data are tabulated in Table LV. 

Because of the ability of ion-selective electrodes to measure the activity of free ions, it has been possible to obtain thermodynamic formation constants and to have information on the number of binding sites and the stoichiometries of complexes. Thus, formation constants have been calculated for copper(II) complexes with glycine, glutamic acid and tris(hydroxymethyl)aminomethane [420,421]. 

Interaction of a copper complex of glycine with ethanal yields the threo and erythro isomers in the ratio of 2 1. They are separated on the basis of their differences in solubility ... 

The copper complex of glycine has been used for the synthesis of j3-hydroxy-ot-amino acids. Under alkaline conditions the carbanion (1) formed from the complex adds to aliphatic and aromatic aldehydes, as in the formation of threonine (2) [18]. Further work on this reaction has shown that the protons on nitrogen in (1) also dissociate under the basic conditions and this has led to an improved procedure which employs the tridentate complex (3), having the double protection of Schiff s base and chelate formation [19]. 

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