Purification and characterization of calmodulin from sea urchin spermatozoa

Abstract
Calmodulin was purified to apparent homogeneity from sea urchin spermatozoa by heat-treatment at 85.degree. C, ammonium sulfate precipitation at pH 4.2, DEAE-Sephacel chromatography and gel filtration on Sephadex G-100. Approximately 8.3 .mu.g calmodulin were recovered per 1010 sperm cells. The sperm calmodulin had an apparent MW of 17,800. The purified calmodulin activated calmodulin-deficient phosphodiesterase from pig coronary arteries, with 1/2 maximal activation occurring at approximately 40 ng calmodulin/ml. Trifluoperazine inhibited the sperm calmodulin activity. Evidently calmodulin is present in high amounts in sea urchin spermatozoa, and is essentially the same as the calmodulin isolated from various other tissues.