Letter | Published:

Isophosphorylase

Nature volume 162, pages 297298 (21 August 1948) | Download Citation

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Abstract

BOTH pure potato phosphorylase1 and crystalline muscle phosphorylase2 produce from glucose-1-phosphate a non-branched polysaccharide containing only α-1,4-glucosidic links and resembling amylose. By the action of extracts of yeast3, of heart, brain or liver4, branched polysaccharides are obtained containing up to 10 per cent of α-1,6-glucosidic linkages and resembling glycogen. In 1942, Meyer and Bernfeld5 reported the presence of an enzyme in yeast which brings about the phosphorolysis of the terminal α-1,6-glucosidic links of residual dextrin (the final degradation product of amylopectin by β-amylase). A purified potato phosphorylase was not able to effect this reaction. It was therefore concluded5 that there are two different phosphorylases, one of which effects the fission or synthesis of α-1,4-glucosidic links, the other the α-1,6-glucosidic links involved in branching. Cori6 has found an enzyme in liver extract and also in heart extract Which he calls the ‘branching factor', and which is able to produce glycogen by simultaneous action with the crystalline muscle phosphorylase. Haworth, Peat and Bourne7 have described a thermolabile factor which they term the 'Q' and to which they attribute the property of synthesizing the α-1,6-glucosidic links in amylopectin. Their 'Q enzyme' has, in addition, an amylatic action.

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Author information

Affiliations

  1. Laboratory of Inorganic and Organic Chemistry, University, Geneva. April 22.

    • P. BERNFELD
    •  & A. MEUTÉ MÉ DIAN

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DOI

https://doi.org/10.1038/162297b0

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