Rapid purification of canine cardiac sarcoplasmic reticulum Ca2+-ATPase

A pure, enzymatically active Ca2+-dependent adenosine triphosphatase (Ca2+-ATPase) has been isolated from canine ventricular sarcoplasmic reticulum. In contrast to that derived from skeletal muscle, the Ca2+-ATPase from cardiac sarcoplasmic reticulum was more active when solubilization and subsequent purification took place in the presence of its substrates, Ca2+ and ATP. Cholate- or deoxycholate-solubilized Ca2+-ATPase is recovered following rapid glycerol dilution and centrifugation. The Ca2+-ATPase is stable and possesses hydrolytic capacities up to 4 mumol/mg/min. Sodium dodecyl sulfate-polyacrylamide gels reveal the presence of one protein in the range of 95,000 to 100,000 daltons. This method also yields purified Ca2+-ATPase from fast skeletal muscle of similar activities to those reported by other laboratories.