Amino acids aminotransferase

In another procedure, D-amino acid oxidase (52) is usehil to produce L-amino acids from DL-amino acids. a-Ketocarboxylic acids which are formed by the action of enzymes on D-amino acids, are aminated to form L-amino acids by coupling through the action of amino acid aminotransferases (53). 

Figure 8.11 Five near-equilibrium reactions involved in transamination of five different amino adds. Three enzymes are involved in these reactions (1) alanine aminotransferase (2) aspartate aminotransferase (3) branched-chain amino acid aminotransferase, i.e. one enzyme catalyses the three reactions. (The branched-chain amino acids are essential.)...

This enzyme [EC 2.6.1.21], also known as D-aspartate aminotransferase, D-amino acid aminotransferase, and D-amino acid transaminase, catalyzes the reversible pyridoxal-phosphate-dependent reaction of D-alanine with a-ketoglutarate to yield pyruvate and D-glutamate. The enzyme will also utilize as substrates the D-stereoisomers of leucine, aspartate, glutamate, aminobutyrate, norva-hne, and asparagine. See o-Amino Acid Aminotransferase... 

Branched-Chain Amino Acid Aminotransferase A. E. Braunstein (1973) The Enzymes, 3rd ed., 9, 379. 

BRANCHED-CHAIN AMINO ACID AMINOTRANSFERASE LEUCINE DEHYDROGENASE LEUCINE KINETICS RROTEIN TURNOVER KINETICS SAAM... 

PHENYLALANINE AMINOTRANSFERASE PHENYLALANINE AMMONIA-LYASE PHENYLALANINE DECARBOXYLASE PHENYLALANINE DEHYDROGENASE PHENYLALANINE MONOOXYGENASE PHENYLALANINE RACEMASE PHENYLALANINE AMINOTRANSFERASE AROMATIC AMINO ACID AMINOTRANSFERASE... 

Transamination Removal of the amino groups of all three amino acids is catalyzed by a single enzyme, branched-chain a-amino acid aminotransferase. 

A transaminase patented by Celgene Corporation (Warren, NJ), called an co-aminotransferase [(co-AT)E.C. 2.6.1.18] does not require an a-amino acid as amino donor instead it requires a primary amine and hence has the ability to produce chiral amines.125 126 A similar co-AT from Vibrio fluvialis has been described for the production of chiral amines along with chiral alcohols when coupled with AdH or chiral amino acids when coupled with an a-amino acid aminotransferase.127130 Another co-AT, ornithine (lysine) aminotransferase (E.C. 2.6.1.68), has been described for the preparation of a chiral pharmaceutical intermediate used in the synthesis of Omapatrilat, a vasopep-tidase inhibitor developed by Bristol-Myers Squibb, as well as the UAA A1 -piperidinc-6-carboxylic acid.131-132... 

Eden, A., Van Nedervelde, L., Drukker, M., Benvenisty, N., Debourg, A. (2001) Involvement of branched-chain amino acid aminotransferases in the production of fiisel alcohols during fermentation in yeast. Applied Microbiology and Biotechnology, 55, 296-300. 

This chapter focuses initially on the catabolism of the amino acids. Aminotransferases can be used to catalyse the first step in the breakdown of nearly all of the amino acids. Lysine catabolism, in contrast, does not begin with an aminotrans-feraseamino acids can be catabolized via more than one pathway. Glutamate catabolism, for example, can begin by reactions catalyzed by glutamate oxaloacetate aminotransferase or glutamate dehydrogenase. 

The results suggested that a group from fhe profein abstracfs a proton from fhe a posihon and transfers if on fhe same side of fhe n system (suprafacial transfer), adding it to the si face of fhe C=N group as shown in Fig. 14-8. Later, fhe same stereospecific proton transfer was demon-sfrafed for the PLP present in the holoen-zyme. Not surprisingly, the D-amino acid aminotransferase adds the proton to the re face of the C = N group. 

Alanine racemase is a bacterial enzyme that catalyzes racemization of l- and d-alanine, and requires pyridoxal 5 -phosphate (PLP) as a cofactor. The enzyme plays an important role in the bacterial growth by providing D-alanine, a central molecule in the peptidoglycan assembly and cross-linking, and has been purified from various sources15 161. The enzyme has been used for the production of stereospecifically deuterated NADH and various D-amino acids by combination of L-alanine dehydrogenase (E. C. 1.4.1.1), D-amino acid aminotransferase (E. C. 2.6.1.21), and formate dehydrogenase (E.C. 1.2.1.2)I17, 18. ... 

Figure 17-4. Synthesis of D-amino acids from a-keto acid, formate, NAD+, D-alanine, and ammonia by coupling of u-alanine dehydrogenase (AlaDH), formate dehydrogenase (FDH), alanine racemase (AlaR), and D-amino acid aminotransferase (d-ATA).

A simple procedure was established for the synthesis of various D-amino adds by means of four types of thermostable enzymes alanine racemase, D-amino acid aminotransferase 49, 501, L-alanine dehydrogenase 51, and formate dehydrogenase (Fig. 17-4) 171. The commercial preparation of formate dehydrogenase from Candida boidinii used by Wichmanri et al. 38 is not sufficiently stable. However, Galkin et al.1521 doned and expressed the gene of thermostable formate dehydrogenase in E. coli. 

Nakajima et al.[9S have developed an efficient method for the synthesis of various d-amino acids from the corresponding a-keto acids and ammonia by coupling of four enzyme reactions catalyzed by D-amino acid aminotransferase l99, glutamate racemase179 91 ], glutamate dehydrogenase and formate dehydrogenase (Fig. 17-10). Various D-amino acids are produced by this method. Under the optimum conditions established by Nakajima et al. 98), D-enantiomers of valine, alanine, a-aminobutyrate,... 

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