Studies on the flagellar ATPase of bull spermatozoa: extraction and characterization

Adenosine triphosphatase (ATPase) activity of flagella isolated from ejaculated bull sperm was solubilized by 5 min exposure to 0.6 M KCl at 4 degrees C. ATPase activity in the flagellar extract was characterized with respect to enzyme, substrate, activator ion, salt, and hydrogen ion concentration. Flagellar extract required the presence of a divalent cation for activity: Mg2+, Ca2+, or Mn2+ could function as activator, but Zn2+ or Cd2+ could not. Magnesium-activated ATPase was maximal in the presence of Mg2+ and ATP in equimolar concentrations and at alkaline pH. Calcium activated ATPase was maximal over a wide range of Ca2+:ATP ratios and at pH 8.0. The presence of increasing concentrations of Na+ and/or K+ ions in the assay medium (0.5-300 mM) had no effect on the ATPase activity of flagellar extract.