Phosphorylase is a family of allosteric enzymes that catalyze the production of glucose-1-phosphate from a polyglucose such as glycogen, starch or maltodextrin.

Function

More generally, phosphorylases are enzymes that catalyze the addition of a phosphate group from an inorganic phosphate (phosphate+hydrogen) to an acceptor. Do not confuse this enzyme with a phosphatase or a kinase. A phosphatase removes a phosphate group from a donor, while a kinase transfers a phosphate group from a donor (usually ATP) to an acceptor.

Types

The phosphorylases are named by prepending the name of the substrate, e.g. glycogen phosphorylase, starch phosphorylase, maltodextrin phosphorylase.

All known phosphorylases share catalytic and structural properties http://www.expasy.org/cgi-bin/nicedoc.pl?PDOC00095.

Activation

Phosphorylase a is the active form of glycogen phosphorylase that is derived from the phosphorylation of the inactive form, phosphorylase b.

Pathology

Some disorders are related to phosphorylases:

• Glycogen storage disease type V - muscle glycogen
• Glycogen storage disease type VI - liver glycogen

External links