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Phosphorylase b from rabbit muscle

lyophilized powder, ≥20 units/mg protein

α-Glucan Phosphorylase, 1,4-α-D-Glucan:orthophosphate α-D-glucosyltransferase, Glycogen Phosphorylase
CAS Number:
Enzyme Commission number:
EC Number:
MDL number:

Quality Level


lyophilized powder

specific activity

≥20 units/mg protein

mol wt

97,200 Da by calculation

purified by

2× crystallization


~0.01 μmol/mg protein 5′-AMP (This low level will not interfere with phosphorylase and phosphorylase kinase assays.)

foreign activity

phosphoglucomutase ≤1.0%
phosphorylase a ≤10%
phosphorylase kinase ≤0.5%
phosphorylase phosphatase, debrancher enzyme, AMPase and ATPase ≤0.1%

storage temp.


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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.
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.


5 mg in glass bottle
10, 25, 100 mg in poly bottle
Package size based on protein content.

Biochem/physiol Actions

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.

Unit Definition

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.)

Physical form

Lyophilized powder containing lactose, 5′-AMP, and Mg(OAc)2 (10 μmole per 100 mg protein)

Storage Class Code

13 - Non Combustible Solids



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

Certificate of Analysis

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Certificate of Origin

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