This transferase enzyme catalyzes the phosphorylation of hexose sugars. More specifically, it phosphorylates the dextrorotatory versions of fructose, glucose, mannose and glucosamine. This enzyme is found throughout all body tissues. In humans, genetic hexokinase deficiency causes a type of hemolytic (red blood cell-destroying) anemia and has been linked to certain types of diabetes.
Hexokinase is found in the first step of glycolysis. Responsible for the transfer of a phosphoryl group from ATP to various hexoses, it requires a divalent metal ion such as Mg2+ or Mn2+ (as do all kinases). It is inhibited by glucose 6-phosphate and activated by insulin.
The reaction of hexokinase in glycolysis is the phosphorylation of glucose to glucose 6-phosphate. It is an irreversable step. The conditions for this reaction are as follows:
- standard conditions: -4.0 kcal/mol
- physiological conditions: -8.0 kcal/mol
Some of the information in this writeup was taken from the science dictionary at http://biotech.icmb.utexas.edu/; I oversaw the development of the dictionary (the website was mothballed in 1998) and I believe I wrote the entry this is based on.