P1,P5-Di(adenosine-5')pentaphosphate, a Potent Multisubstrate Inhibitor of Adenylate Kinase

P¹,P⁵-Di(adenosine-5')pentaphosphate, a Potent Multisubstrate Inhibitor of Adenylate Kinase

From the Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755

Abstract

Rabbit muscle adenylate kinase is potently inhibited by P¹,P⁵-di(adenosine-5')pentaphosphate (Ap₅A) but not by the homologs of this compound with fewer phosphoryl groups in the polyphosphate bridge and not by adenosine 5'-pentaphosphate. The inhibition by Ap₅A is competitive with respect to both of the substrates, AMP and ATP. The association constant for the binding of Ap₅A to adenylate kinase is about 4 x 10⁸ m^-1 at 24° and pH 8.0.