This is a type of enzyme that catalyzes (accelerates) reactions where phosphate group transfers are made, specifically hexokinase works on the phosphorylation of glucose to form a new compound called “glucose-6-phosphate” (because the phosphorus group is located on carbon number 6 of glucose). In the biochemical reaction that the action of hexokinase is needed, it is the process of glycolysis, or glucose degradation specifically in muscle and other tissues such as brain, red blood cells and among others, glucose degradation results in the production of pyruvic acid or pyruvate; the reverse glycolysis reaction results in the formation of glucose from non-carbon compounds or glycogeneogenesis and is produced in the liver.

Now then, this enzyme was mentioned as hexokinase due to the etymological meaning of the word, “kinase” indicates that the enzyme produces phosphorylation (adds a phosphorous group to the reaction), and “hexo” refers to the reaction being given in hexoses, these are a group of carbohydrates or sugars that are composed of 6 carbons, within this group are glucose, fructose, mannose among others. One of the essential chemical compounds for the proper functioning of the hexokinase is magnesium, this inhibits the negative charges of oxygen or ATP, thus facilitating the combination of the phosphate group with the hexose, for this reason it does not work without the presence of magnesium.

Hexokinase has an isoenzyme (they are different but fulfill the same function) this is called glucokinase, the difference between the two is the location site, hexokinase is found in all cellular tissues that require glucose as an energy source, while that glucokinase is only located within hepatocytes, these are cells that make up what is hepatic tissue (liver). Both fulfill the same function, phosphorylate glucose so that it does not escape from the cell, trapping it to execute the glycolysis process, another important difference between both enzymes is the compound that inhibits its function, hexokinase stops working if it has in high concentrations glucose-6-phosphate, while glucokinase is inhibited by high amounts of fructose-6-phosphate.