Glycogen debranching enzyme: Difference between revisions

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Revision as of 15:34, 27 March 2012

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A '''debranching enzyme''' is a molecule that helps facilitate the breakdown of [[glycogen]], which serves as a store of glucose in the body, through glucosyltransferase and glucosidase activity. Together with [[phosphorylase]]s, debranching enzymes mobilize [[glucose]] reserves from glycogen deposits in the muscles and liver. This constitutes a major source of energy reserves in most organisms. Glycogen breakdown is highly regulated in the body, especially in the [[liver]], by various hormones including [[insulin]] and [[glucagon]], to maintain a homeostatic balance of blood-glucose levels.<ref name="Hers"/> When glycogen breakdown is compromised by mutations in the glycogen debranching enzyme, metabolic diseases such as [[Glycogen storage disease type III]] can result.<ref name="Song"/><ref name="Bao"/>

Glucosyltransferase and glucosidase are performed by a single [[enzyme]] in mammals, yeast, and some bacteria, but by two distinct enzymes in ''[[E. coli]]'' and other bacteria, complicating nomenclature. Proteins that catalyze both functions are referred to as glycogen debranching enzymes (GDEs). When glucosyltransferase and glucosidase are catylizedcatalyzed by distinct enzymes, "glycogen debranching enzyme" usually refers to the glucosidase [[enzyme]]. In some literature, an enzyme capable only of glucosidase is referred to as a "debranching enzyme".<ref name=Woo/>

== Function ==