Inactivation of bacterial D-amino acid transaminase by beta-chloro-D-alanine.
Purified D-amino acid transaminase from Bacillus sphaericus catalyzes an alpha,beta elimination from the D isomer of beta-chloroalanine to yield equivalent amounts of pyruvate, chloride, and ammonia; the L isomer of chloroalanine is not a substrate for this transaminase. During the beta elimination there is a synchronous loss in enzyme activity; the Kinact for beta-chloroalanine was estimated to be about 10 micrometers. The alpha-aminoacrylate-Schiff base intermediate formed after beta elimination of chloride ion is probably the key intermediate that partitions between one inactivation event for every 1500 turnovers. In the presence of D-alanine and alpha-ketoglutarate, which are good substrates for the transaminase activity of this enzyme, beta-chloroalanine is a potent, competitive inhibitor (K1 = 10 micrometers) with D-alanine and a weak, uncompetitive inhibitor with alpha-ketoglutarate.
D000409:Alanine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000596:Amino Acids / Q000032:analysis; D001407:Bacillus / Q000201:enzymology; D007656:Ketoglutaric Acids / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D013237:Stereoisomerism; D000637:Transaminases / Q000037:antagonists & inhibitors* / Q000378:metabolism
D000596:Amino Acids; D007656:Ketoglutaric Acids; D000637:Transaminases; D000409:Alanine