Inactivation of bacterial D-amino acid transaminases by the olefinic amino acid D-vinylglycine.
D-Vinylglycine (2-amino-3-butenoate) functions as a transamination substrate and irreversible inactivator of the homogeneous pyridoxal phosphate-dependent D-amino acid transaminases from Bacillus subtilis and Bacillus sphaericus. In the absence of alpha-ketoglutarate as co-substrate, vinyl-glycine causes little if any inactivation of either enzyme; in the presence of excess alpha-ketoglutarate, both enzymes are inactivated with pseudo-first order kinetics. The limiting rate constant for inactivation of the B. sphaericus enzyme is 1.9 min-1, for the B. subilis enzyme it is 0.36 min-1. The number of catalytic events before inactivation is about 450 for the B. sphaericus enzyme and about 800 for the B. subtilis enzyme; that is, about 0.2% inactivation in each catalytic cycle for the former enzyme and 0.15% for the latter. Comparisons are made with the L-aspartate amino-transferase from pig heart which is inactivated completely in one catalytic cycle and the L-alanine aminotransferase which is not inactivated in many cycles. Comparisons are also made between the likely mode of D-transaminase inactivation produced by vinylglycine and the mode of inactivation induced by beta-chloro-D-alanine.
D000596:Amino Acids; D000613:Aminobutyrates / Q000494:pharmacology*; D001407:Bacillus / Q000201:enzymology*; D001412:Bacillus subtilis / Q000201:enzymology*; D005998:Glycine / Q000031:analogs & derivatives; D007700:Kinetics; D013045:Species Specificity; D013237:Stereoisomerism; D000637:Transaminases / Q000037:antagonists & inhibitors*
D000596:Amino Acids; D000613:Aminobutyrates; C006507:vinylglycine; D000637:Transaminases; D005998:Glycine