|Topic:||Regulation of Glycolysis .|
The reactions catalyzed by hexokinase (or glucokinase), PFK-1 and PK all proceed with a relatively large free energy decrease. These non-equilibrium reactions of glycolysis would be ideal candidates for regulation of the flux through glycolysis. Indeed, in vitro studies have shown all three enzymes to be allosterically controlled.
Regulation of hexokinase, however, is not the major control point in glycolysis in tissues other than the liver. This is due to the fact that large amounts of G6P are derived from the breakdown of glycogen (the predominant mechanism of carbohydrate entry into glycolysis in skeletal muscle) and, therefore, the hexokinase reaction is not necessary. Regulation of PK is important for reversing glycolysis when ATP is high in order to activate gluconeogenesis. As such this enzyme catalyzed reaction is not a major control point in glycolysis. The rate limiting step in glycolysis is the reaction catalyzed by PFK-1.
COPYRIGHT ©2019 . All Rights Reserved.