Reaction of Pyridoxamine - Pyruvate Transaminase Sulfhydryl Reagents

Wherever the point has been examined (e.g. References l-6), pyridoxal phosphate enzymes have been found to require free sulfhydryl groups for activity. The functional role played by these groups, however, has not been clear. In glutamate-oxaloacetate transaminase, which has been studied most extensively, no spectrophotometric or enzymatic evidence for their participation in coenzyme binding was at first obtained (4, 5). Recent preliminary results, however, indicated that certain free sulfhydryl groups are required for the binding of pyridoxamine phosphate by the apotransaminase (6). To further clarify the role of sulfhydryl groups in enzymatic transamination, we have studied the simplified case provided by