Glucokinase of rabbit liver: purification and properties

Abstract

It has been recently shown that in rat liver there are two enzymes which phosphorylate glucose to glucose 6-phosphate. One o f them is a hexokinase with a great af f ini ty for glucose and, like those o f other animal tissues it is inhibited by glucose 6- phosphate; the other one, named glucokinase, has a low affinity for glucose, is not inhibited by glucose 6phosphate, and appears to be responsible for glycogen synthesis from glucose in liver (1). Hexokinase activity exists in both fetal and adult liver whereas glucokinase develops after birth (2). Results from several laboratories have shown that glucokinase activity disappears as a result of fasting and diabet,es and reappears after refeeding or insulin administration, respectively (l-9), and that this reap- pearance involves synthesis de nouo of the enzyme apparently mediated by insulin (3, 4, 6, 10)