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J Gen Physiol. Jan 20, 1952; 35(3): 423–450.
PMCID: PMC2147340

CRYSTALLINE INORGANIC PYROPHOSPHATASE ISOLATED FROM BAKER'S YEAST

Abstract

Crystalline inorganic pyrophosphatase has been isolated from baker's yeast. The crystalline enzyme is a protein of the albumin type with an isoelectric point near pH 4.8. Its molecular weight is of the order of 100,000. It contains about 5 per cent tyrosine and 3.5 per cent tryptophane. It is most stable at pH 6.8. The new crystalline protein acts as a specific catalyst for the hydrolysis of inorganic pyrophosphate into orthophosphate ions. It does not catalyze the hydrolysis of the pyrophosphate radical of such organic esters as adenosine di- and triphosphate, or thiamine pyrophosphate. Crystalline pyrophosphatase requires the presence of Mg, Co, or Mn ions as activators. These ions are antagonized by calcium ions. Mg is also antagonized by Co or Mn ions. The rate of the enzymatic hydrolysis of inorganic pyrophosphate is proportional to the concentration of enzyme and is a function of pH, temperature, concentration of substrate, and concentration of activating ion. The approximate conditions for optimum rate are: 40°C. and pH 7.0 at a concentration of 3 to 4 x 10–3 M Na4P2O7 and an equivalent concentration of magnesium salt. The enzymatic hydrolysis of Na4P2O7 or K4P2O7 proceeds to completion and is irreversible under the conditions at which hydrolysis is occurring. Details are given of the method of isolation of the crystalline enzyme.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Bailey K, Webb EC. Purification and properties of yeast pyrophosphatase. Biochem J. 1944;38(5):394–398. [PMC free article] [PubMed]
  • Goodwin TW, Morton RA. The spectrophotometric determination of tyrosine and tryptophan in proteins. Biochem J. 1946;40(5-6):628–632. [PMC free article] [PubMed]
  • Kay HD. The phosphatases of mammalian tissues: Pyrophosphatase. Biochem J. 1928;22(6):1446–1448. [PMC free article] [PubMed]
  • Mann T. Studies on the metabolism of mould fungi: 1. Phosphorus metabolism in moulds. Biochem J. 1944;38(4):339–345. [PMC free article] [PubMed]

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