Cardiac Myosin Adenosinetriphosphatase Activity
Modifying Factors and Comparison with Skeletal Muscle Myosin Adenosinetriphosphatase ACTIVITY
Cardiac myosin prepared by any one of a number of modifications of the basic Szent-Gyorgyi method and cardiac myosin prepared by the lithium chloride-ammonium sulfate technique differ in two important respects: 1) Szent-Gyorgyi-prepared myosin solutions are inhomogeneous by both chemical and immunologic criteria; 2) the ATPase activity of Szent-Gyorgyi-prepared myosin is low in comparison to lithium chloride-ammonium sulfate prepared cardiac myosin. Evidence is presented in this paper showing that the reduced ATPase activity of Szent-Gyorgyi-prepared cardiac myosin is the result of inhibition of the enzyme, possibly by a nucleotide contaminant, and a "diluting" effect of other nitrogen-containing contaminants of low specific activity.
Many earlier studies indicate that cardiac and skeletal muscle myosin prepared by the Szent-Gyorgyi method differed strikingly in their ATPase activities. Comparison of lithium chloride-ammonium sulfate prepared cardiac and skeletal muscle myosin shows that skeletal muscle myosin has a slightly but significantly higher ATPase activity than canine cardiac myosin. A methodologic error was not excluded as the cause of this discrepancy. In a number of other characteristics, canine cardiac and skeletal muscle myosin ATPase activity was virtually identical.
- purification of canine cardiac myosin characterization of cardiac and skeletal myosin
- myosin enzyme activity kinetics of myosin ATPase
- contractile protein
- myosin contamination
- adenosinetriphosphatase systems
- fractionation of myosin biochemistry of myosin
- Accepted March 7, 1966.
- © 1966 American Heart Association, Inc.