DIVALENT CATION ACTIVATION OF FLAGELLAR ATP-PHOSPHOHYDROLASE FROM BULL SPERM

The apparently inconsistent reports on flagellar ATPase properties may be resolved by elimination of adenylate kinase from the system. Removal of the adenylate kinase from alkaline M/2 KCl extracts of bull sperm flagella yields a spermosin‐ATPase which liberates only the terminal phosphate of ATP. In any case spermosin is preferentially activated by calcium. However, combination of spermosin with flactin (e.g., by addition of digitonin and MgCl2 to the extraction medium) produces an ATPase much more highly activated by magnesium. But flactospermosin has so far resisted purification from its adenylate kinase contaminant. In divalent cation activation, pH optima and nature of ATP hydrolysis, the flagellar contractile protein system closely parallels the muscle system. Copyright © 1969 Wiley‐Liss, Inc.