Glycogen biosynthesis in human skeletal muscle

Abstract

Glycogen Biosynthesis in Human Skeletal Muscle

Human skeletal muscle has the two en- zymatic forms of glycogen synthetase (UDPG: a-l,4-glucan a-4-glucosyltransferase) as evidenced by the different levels of activity found in several human samples. These levels of enzyme activity measured in the presente or absence of glucose-6-P do not show any relationship with the tissue glycogen contení in our ex­ perimental conditions.

The kinetic constants determined for the D form of human muscle glycogen synthetase, Km for sustrate and Ka of glucose-6-P do not differ significantly from those determined for the same from of the enzyme from muscle of other mammal species.

The transformation system from the D to the I form of the enzyme has been detected by preincubation of tissue ex- tracts in the presence of mercaptoethanol. The opposite system is indirectly infered by the different levels of activity measured in the presence or absence of glucose-6-P.