Interaction in vitro of scallop muscle arginine kinase with filamentous actin

Scallop muscle arginine kinase binds to F-actin from mollusc and rabbit muscle in vitro. One site of interaction appears to be located in residues 305-325 of a C-terminal fragment (residues 285-375) of actin. The binding is hindered in the presence of arginine, Mg(2+)-ADP and NO3-, which form a dead-end complex with the enzyme. F-actin inhibits the enzyme activity non-competitively with respect to Mg(2+)-ATP. As a function of arginine concentration, the inhibition is of the mixed type, where Km is affected more than Vmax.