Figure 4.

Inhibition of serine racemase by PLP inhibitors and sulfhydryl oxidation. (A) Enzyme activity was monitored at 37°C in a medium containing 50 mM Tris⋅HCl, pH 8.0/20 mM l-serine, 100 μg/ml purified enzyme, 1 mM EDTA, 2 mM DTT, and 10 μM PLP and different concentrations of either AOAA (○) or hydroxylamine (•). (B) Reaction medium and conditions were as described in A, except that DTT was omitted from the last step of the enzyme preparation. The enzyme was preincubated for 10 min in the presence of different concentrations of oxidized glutathione (GSSG).