Description
Glycogen branching enzyme is an enzyme that adds branches to the growing glycogen molecule during the synthesis of glycogen, a storage form of glucose. More specifically, during glycogen synthesis, a glucose 1-phosphate molecule reacts with uridine triphosphate (UTP) to become UDP-glucose, an activated form of glucose. The activated glucosyl unit of UDP-glucose is then transferred to the hydroxyl group at the C-4 of a terminal residue of glycogen to form an α-1,4-glycosidic linkage, a reaction catalyzed by glycogen synthase. Importantly, glycogen synthase can only catalyze the synthesis of α-1,4-glycosidic linkages. Since glycogen is a readily mobilized storage form of glucose, the extended glycogen polymer is branched by glycogen branching enzyme to provide glycogen breakdown enzymes, such as glycogen phosphorylase, with a large number of terminal residues for rapid degradation. Branching also importantly increases the solubility and decreases the osmotic strength of glycogen.
Abbr
Glycogen branching enzyme, Recombinant (Bacillus subtilis)
Source
Bacillus subtilis subsp. subtilis str. 168
Form
Supplied in 3.2 M ammonium sulphate
Enzyme Commission Number
EC 2.4.1.18
Molecular Weight
77485.4 Da
Purity
> 95 % as judged by SDS-PAGE
Unit Definition
One unit is defined as the amount of enzyme required to cause a fall of 1.0 absorbance units, where the reaction mixture comprises 3.33 mg/mL starch in 41.7 mM sodium phosphate buffer, pH 7.5, and where 0.24 mL of the reaction mixture is withdrawn at each time point, and mixed with 1.0 mL of deionised water and 0.2 mL of iodine reagent immediately prior to reading at 660 nm.
Storage
Store at 4°C (shipped at room temperature)
Preparation Instructions
Agitate bottle sufficiently to fully homogenise enzyme precipitate before use. Dilute in 50 mM sodium phosphate buffer, pH 7.5, containing 2 mg/mL BSA. Do not dilute in water.
Synonyms
Branching enzyme, amylo-(1,4→1,6)-transglycosylase; Q-enzyme; α-glucan-branching glycosyltransferase; amylose isomerase; enzymatic branching factor; branching glycosyltransferase; enzyme Q; glucosan transglycosylase; glycogen branching enzyme; plant branching enzyme; α-1,4-glucan:α-1,4-glucan-6-glycosyltransferase; starch branching enzyme; 1,4-α-D-glucan:1,4-α-D-glucan 6-α-D-(1,4-α-D-glucano)-transferase
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