JBC, Vol. 252, Issue 5, 1571-1575, Mar, 1977
Inactivation of bacterial D-amino acid transaminases by the olefinic amino acid D-vinylglycine
T. S. Soper, J. M. Manning, P. A. Marcotte and C. T. Walsh
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.