Starch phosphorylase is a form of phosphorylase similar to glycogen phosphorylase, except that it acts upon starch instead of glycogen.
The plant alpha-glucan phosphorylase, commonly called starch phosphorylase (EC 2.4.1.1), is largely known for the phosphorolytic degradation of starch. Starch phosphorylase catalyzes the reversible transfer of glucosyl units from glucose-1-phosphate to the nonreducing end of alpha-1,4-D-glucan chains with the release of phosphate. Two distinct forms of starch phosphorylase, plastidic phosphorylase and cytosolic phosphorylase, have been consistently observed in higher plants.
Crit Rev Biotechnol. 2009;29(3):214-24. Starch phosphorylase: role in starch metabolism and biotechnological applications.
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in staple foods such as wheat, potatoes, maize (corn), rice, and cassava (manioc).
Glycogenolysis is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1). Glycogen branches are catabolized by the sequential removal of glucose monomers via phosphorolysis, by the enzyme glycogen phosphorylase.
Glucose 6-phosphate is a glucose sugar phosphorylated at the hydroxy group on carbon 6. This dianion is very common in cells as the majority of glucose entering a cell will become phosphorylated in this way.
In biochemistry, phosphorylases are enzymes that catalyze the addition of a phosphate group from an inorganic phosphate (phosphate+hydrogen) to an acceptor.
Glycogenesis is the process of glycogen synthesis, in which glucose molecules are added to chains of glycogen for storage. This process is activated during rest periods following the Cori cycle, in the liver, and also activated by insulin in response to high glucose levels.
Glycogen phosphorylase is one of the phosphorylase enzymes. Glycogen phosphorylase catalyzes the rate-limiting step in glycogenolysis in animals by releasing glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond. Glycogen phosphorylase is also studied as a model protein regulated by both reversible phosphorylation and allosteric effects.
Glucose 1-phosphate is a glucose molecule with a phosphate group on the 1'-carbon. It can exist in either the α- or β-anomeric form.
Glycogen synthase is a key enzyme in glycogenesis, the conversion of glucose into glycogen. It is a glycosyltransferase that catalyses the reaction of UDP-glucose and n to yield UDP and n+1.
Phosphorolysis is the cleavage of a compound in which inorganic phosphate is the attacking group. It is analogous to hydrolysis.
1,4-alpha-glucan-branching enzyme, also known as brancher enzyme or glycogen-branching enzyme is an enzyme that in humans is encoded by the GBE1 gene.
β-Amylase is an enzyme with the systematic name 4-α-D-glucan maltohydrolase. It catalyses the following reaction:
Phosphorylase kinase (PhK) is a serine/threonine-specific protein kinase which activates glycogen phosphorylase to release glucose-1-phosphate from glycogen. PhK phosphorylates glycogen phosphorylase at two serine residues, triggering a conformational shift which favors the more active glycogen phosphorylase “a” form over the less active glycogen phosphorylase b.
Myophosphorylase or glycogen phosphorylase, muscle associated (PYGM) is the muscle isoform of the enzyme glycogen phosphorylase and is encoded by the PYGM gene. This enzyme helps break down glycogen into glucose-1-phosphate, so it can be used within the muscle cell. Mutations in this gene are associated with McArdle disease, a glycogen storage disease of muscle.
In enzymology, a 1,3-beta-D-glucan phosphorylase is an enzyme that catalyzes the chemical reaction
In enzymology, a cellobiose phosphorylase is an enzyme that catalyzes the chemical reaction
In enzymology, a starch synthase is an enzyme that catalyzes the chemical reaction
α-Glucans (alpha-glucans) are polysaccharides of D-glucose monomers linked with glycosidic bonds of the alpha form. α-Glucans use cofactors in a cofactor site in order to activate a glucan phosphorylase enzyme. This enzyme causes a reaction that transfers a glucosyl portion between orthophosphate and α-I,4-glucan. The position of the cofactors to the active sites on the enzyme are critical to the overall reaction rate thus, any alteration to the cofactor site leads to the disruption of the glucan binding site.
Starch synthase (maltosyl-transferring) is an enzyme with systematic name alpha-maltose 1-phosphate:(1->4)-alpha-D-glucan 4-alpha-D-maltosyltransferase. This enzyme catalyses the following chemical reaction
The enzyme exo-(1→4)-α-D-glucan lyase (EC 4.2.2.13, α-(1→4)-glucan 1,5-anhydro-D-fructose eliminase, α-1,4-glucan exo-lyase, α-1,4-glucan lyase, GLase) is an enzyme with systematic name (1→4)-α-D-glucan exo-4-lyase (1,5-anhydro-D-fructose-forming). This enzyme catalyses the following chemical reaction
Barbara Illingworth Brown was an American biochemist. She worked primarily at Washington University in St. Louis.
