Peptide y-glutamyl

In the folate coenzymes, the pteridine ring is fully reduced to tetrahydro-folate, although the oxidized form, dihydrofolate, is an important metabolic intermediate. In the reactions of thymidylate synthetase (Section 10.3.3) and methylene tetrahydrofolate reductase (Section 10.3.2.1), the pteridine ring has a redox role in the reaction. The folate coenzymes are conjugated with up to six additional glutamate residues, finked by y-glutamyl peptide bonds. 

The identification of these peptides, particularly S-(2-carboxypropyl) glutathione, provides the first suggestion of a biosynthetic pathway. L-Cys-teine, either free or as the y-glutamyl peptide, might combine with methacrylic acid or its coenzyme A ester (an intermediate of valine... 

Fio. 2. Identification of y-glutamyl peptide links by the Hofmann rearrangement. 

GGT is present (in decreasing order of abundance) in proximal renal tubule, liver, pancreas, and intestine. The enzyme is present in cytoplasm (microsomes), but the larger fraction is located in the cell membrane and may transport amino acids and peptides into the cell across the cell membrane in the form of y-glutamyl peptides. It may also be involved in some aspects of glutathione metabolism. ... 

Inoue, M., Hiratake, J., and Sakata, K., Synthesis and characterization of intermediate and transition-state analogue inhibitors of y-glutamyl peptide ligases, Biosci. Biotechnol. Biochem., 63, 2248, 1999. 

Therefore, we have isolated the two products and have assessed their ability to act as substrates for two y-GH s isolated from chick pancreas and hog kidney. These two hydrolases differentially cleave the poly-y-glutamate chain at two distinct y-glutamyl peptide bonds (Scheme HI, open arrow (hog kidney) and filled arrow (chick pancreas)). The results of these enzyme-catalyzed hydrolyses provides strong evidence for the structures assigned to the reaction products as AMPteGlu-y Glu... 

To chemically synthesize L-theanine from PCA, several procedures may be followed. A classical synthesis of y-glutamyl peptides has been developed from carbo-... 

Folic acid cofactors (1) are derived from tetrahydropteroic acid linked to the a-amino function of poly-y-glutamyl peptides of varying chain length (n = 1-8). The absolute configuration at C-6 for tetrahydrofolate (H4-folate) which should also include the pteroyl polyglutamates, has been defined as S) by X-ray studies on... 

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