Description_x000D_ Application_x000D_ Phosphorylase b is used to study the conversion mechanism of inactive phosphorylase b to active phosphorylase in muscle. Phosphorylase b is used to study which factors influence the conversion of phosphorylase b to phosphorylase a such as temperature, AMP, fluoride and detergents. It is used to study phosphorylase b deficiency mutations._x000D_ The enzyme from Sigma has been used in the calibration of Sepharose C1-6B columns while studying the molecular weight of methylamine dehydrogenase subunits. It has been used in ion mobility-mass spectrometry studies of phosphorylase B ions that have been generated with supercharging reagents, in charge-reducing buffer. It has also been used for the preparation of p32 labeled phosphorylase A using phosphorylase kinase and [32P]ATP._x000D_ Packaging_x000D_ 10, 25, 100 mg in poly bottle_x000D_ 5 mg in glass bottle_x000D_ Package size based on protein content._x000D_ Biochem/physiol Actions_x000D_ Phosphorylase b is a non-active form and is present in resting muscle. Phosphorylase b kinase activity increases significantly when the Mg2+:ATP ratio exceeds 1. The breakdown of ATP during muscle contraction is thought to trigger in vivo conversion of phosphorylase b into a. Phosphorylase b is activated by inosine monophosphate._x000D_ Unit Definition_x000D_ One unit will form 1.0 μmole of α-D-glucose 1-phosphate from glycogen and orthophosphate in the presence of 5′-AMP, per min at pH 6.8 at 30 °C measured in a system containing phosphoglucomutase, NADP, and glucose 6-phosphate dehydrogenase. (One μmolar unit is equivalent to approx. 45 Cori units.)_x000D_ Physical form_x000D_ Lyophilized powder containing lactose, 5′-AMP, and Mg(OAc)2 (10 μmole per 100 mg protein)