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P6635 Sigma

Phosphorylase b from rabbit muscle

lyophilized powder, ≥20 units/mg protein

Synonym: α-Glucan Phosphorylase, 1,4-α-D-Glucan:orthophosphate α-D-glucosyltransferase, Glycogen Phosphorylase



Related Categories 2.4.x.x Glycosyltransferases, 2.x.x.x Transferases, Biochemicals and Reagents, Cell Biology, Enzyme Class Index,
Quality Level   PREMIUM
form   lyophilized powder
mol wt   mol wt 97,200 Da by calculation
purified by   2× crystallization
impurities   ~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.   −20°C


Frequently Asked Questions

Frequently Asked Questions are available for this Product.


10, 25, 100 mg in poly bottle

5 mg in glass bottle

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)


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.

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.

Price and Availability

All labs need water

Biomedical Applications
Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 

Frequently Asked Questions

Which document(s) contains shelf-life or expiration date information for a given product?
If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis. These documents are located on the product detail page under Useful Links & Tools. Click on the following link to search for a Certificate of Analysis. Please click the following link to see the details on our Product Dating Information.
How do I get lot-specific information or a Certificate of Analysis?
A Certificate of Analysis is available by lot number and can be obtained through our Advanced Search Option: http://www.sigmaaldrich.com/catalog/AdvancedSearchPage.do
How do I find price and availability?
There are several ways to find pricing and availability for our products.  Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote.  USA customers:  1-800-325-3010 or view local office numbers. 
What is the Department of Transportation shipping information for this product?
Transportation information can be found in Section 14 of the product's (M)SDS. To access the shipping information for this material, use the link on the product detail page for the product, or search here. 
My question is not addressed here, how can I contact Technical Service for assistance?
Use the option to the right to "Ask a Question" by email of a Technical Service Scientist.
Has the amino acid sequence of phosphorylase from rabbit muscle been published?
The sequence has been published. The amino acid composition is: Asp5l, Asn45, Thr35, Ser29, Glu64, Gln31, Pro36, Gly48, Ala63, Cys9, Val62, Met2l, Ile49, Leu79, Tyr36, Phe38, Trp12, Lys48, HiS22, and Arg63. Reference for the sequence and amino acid composition: K. Titani et al., Proc. Nat. Acad. Sci., USA, 74, 4762-4766 (1977) (see attached pdf). Product P1261 is phosphorylase a, which is the tetrameric form. Products P4649 and P6635 are phosphorylase b, the dimeric  form. The sequence information of the subunit would be the same for both forms.
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92210 Timestrip Plus 0 °C
06693 Timestrip Plus -20 °C

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