Functional role of arginine residues in glutamic acid decarboxylase from brain and bacteria.

The arginine-specific reagent phenylglyoxal rapidly inactives glutamic decarboxylase from both mouse brain and E. coli when preincubated with the enzyme at concentrations of 3 mM to 40 mM. The rate of inactivation follows pseudo-first-order kinetics and is dependent upon the concentration of phenylglyoxal. These and other data presented support the idea that arginine residues play a key role in the mechanism of action of glutamic decarboxylase.