Study of the Mg2+-ATPase reaction of myosin using the NMR-31P method. Detection of adenylate kinase activity in a purified myosin subfragment I]

Isolated myosin heads (HMM-S1) were concentrated by ultrafiltration in an "Amicon" cell to a concentration of 120 mg/ml. Incubation of HMM-S1 with ATP in the presence of Mg2+ produced an AMP peak in the spectrum of NMR-31P whose size was increasing linearly with the reaction time. It was demonstrated that after heating of the sample the appearance of AMP in the incubation mixture was due to the presence of a small amount of adenylate kinase (or myokinase) in the purified preparation of HMM-S1.