Comparison of stopped flow and steady state kinetics in the reaction of D-amino-acid oxidase with -chloroalanine.

WALSH et a l . 1 recently showed that D-amino acid oxidase is capable of catalyzing a — ß elimination of HCl from D-/?-chloroalanine as well as oxidative deamination. We have also been studying the behavior of this substrate and we wish to briefly point out one aspect of our findings, namely the difficulties we have had in attempting to correlate the steady state turnover behavior of the reaction with stopped-flow monitored kinetics of enzyme-bound intermediates at 550 nm. Fig. 1 shows the results of anaerobic stoppedflow measurements in which the enzyme is mixed with high and low concentrations of /?-chloroalanine. A reaction trace obtained with D-alanine is also in-