Fructokinase

Fructokinase (/fruc•to•ki•nase/ [-ki´nas]) (EC2.7.1.4), also known as D-fructokinase or D-fructose (D-mannose) kinase, is an enzyme of the liver, intestine, and kidney cortex. Fructokinase is in a family of enzymes called transferases, meaning that this enzyme transfers functional groups; it is also considered a phosphotransferase (or, frequently, a kinase) since it specifically transfers a phosphate group. Fructokinase specifically catalyzes the transfer of a phosphate group from ATP (the substrate) to fructose as the initial step in its utilization. The main role of fructokinase is in carbohydrate metabolism, more specifically, sucrose and fructose metabolism. The reaction equation is as follows: ATP + D-fructose = ADP + D-fructose 1-phosphate. This is notable because in most tissues this reaction is catalyzed by hexokinase, forming instead fructose 6-phosphate.