Glycolysis is internally balanced for oxidation and reduction when extended to the lactate dehydrogenase step. The remaining excess is what it takes to ensure that the reactions proceed in the required direction . All of these reactions are easily reversed by a small change in the relationship of substrate and product concentrations. Three out of the four kinase steps have large negative values, and are driven strongly left to right . These are the reactions which determine the direction of reaction in glycolysis.
Pyruvate kinase clears intermediates out of the pathway.
Catalytic activity is limited at these steps. These enzymes are good targets for regulation and control of the pathway. Regulation of glycolysis These steps are where glycolysis is regulated , meaning that the activity is shut down if ATP is not needed . However, liver contains glucokinase , which is a high K M isozyme of hexokinase, and is not subject to product inhibition . Since the energy demand is low, this can then result in diversion of excess glucose to fat biosynthesis in the liver.