Persistence of adenylate kinase and other enzymes in glycerol extracted muscle

Summary

The use of glycerol extracted muscle allows mechanical studies on the contractile mechanism to be carried out under defined biochemical conditions. It is important to know whether enzymes, other than the myofibrillar ATPase, which act on adenine nucleotides are present in this preparation. Therefore, the effects of glycerol extraction were studied on adenylate kinase and arginine kinase activities in insect fibrillar muscle and on adenylate kinase, creatine kinase and AMP deaminase activities in rabbit psoas muscle. All these activities decreased during glycerol extraction. A substantial part of the activity was lost in the first day of glycerol extraction, after which a very slow rate of loss occurred. There was some indication of a preferential loss from the soluble fraction of the fibres but this was insufficient to explain the biphasic loss. Measurements of the total activity of adenylate kinase in the fibres plus the glycerol medium suggested that some inactivation had occurred. It is also possible that the outer fibres in a bundle are extracted more rapidly than are the inner fibres. All three effects are probably playing a part but we are unable to offer a complete quantitative explanation of the results.