Inactivation of adenylate cyclase by phenylglyoxal and other dicarbonyls. Evidence for existence of essential arginyl residues

Abstract

Rat brain adenylate cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1) activity was markedly reduced when the enzyme was preincubated at 23 degrees C for periods up to 30 min with phenylglyoxyal (2.5-20 mM), an agent that binds specifically to arinyl residues. The kinetics indicated the interaction of phenylgloxal with one arginyl residue was responsible for the inactivation. Protection of inactivation of the enzyme by phenylglyoxal was attained in the presence of ATP and to a lesser extent by ADP and 5'-AMP but not by cyclic-AMP or Mg2+. In addition, 2,3-butanedione and 1,2-hexanedione, compounds that also react with arginyl residues, each inactivated adenylate cyclase to varying degrees. Furthermore, this inactivation was enhanced in the presence of borate ions. These observations strongly suggest that brain adenylate cyclase possesses essential arginyl residues.