Abstract
Pyridoxal kinase from Escherichia. coli KG 980 was inactivated by pyridoxal (PL) as follows : 1) The inactivation of the enzyme was reversible. The inactivation showed an equilibrium reaction pattern with K_<eq> values of 37 to 31 mM^<-1>. 2) The inactivation followed pseudo-first order kinetics with respect to time, and then maximal inactivation was achieved by incubation for 15〜20 min. 3) The results were consistent with a one-step inactivation mechanism. 4) The inactivation was due to the specific binding of PL to one crucial PL binding site, by the formation of Schiff base. 5) The substrate (or analog) did not protect against inactivation with PL. 6) The binding of PL was accompanied by the complete loss of enzyme activity.
