Influence of Starvation and Glucose Load on the Activity of Liver Phosphorylase in Normal and Adrenalectomized Rats

Abstract

RECENTLY, it has been shown by Sutherland et al.^1,2 that liver phosphorylase is acted on by two different enzymes. They found that the inactivation of liver phosphorylase was caused by an enzyme which appeared to be a phosphatase able to split off phosphate from active liver phosphorylase and thus render it inactive. Furthermore, they were able to demonstrate the existence of another enzyme able to reactivate inactive phosphorylase. In an earlier work, Sutherland and Cori³ showed that epinephrine and glucagon play an essential part in the activation of liver phosphorylase, and evidence has since been established for the assumption that epinephrine and glucagon are reacting in some way or other with the reactivating enzyme. The complete mechanism has not yet been worked out, although a recent paper published by Rail, Sutherland and Berthet⁴ has elicited the problem further.