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. 1981 Nov;68(5):1123–1127. doi: 10.1104/pp.68.5.1123

Hexokinase II of Pea Seeds

John F Turner 1, Les Copeland 1
PMCID: PMC426056  PMID: 16662062

Abstract

A second hexokinase (EC 2.7.1.1) was obtained from pea seed (Pisum sativum L. var. Progress No. 9) extracts. The enzyme, termed hexokinase II, had a high affinity (Km, 48 micromolar) for glucose and a relatively low affinity (Km, 10 millimolar) for fructose. The Km for MgATP was 86 micromolar. Mg2+ was required for activity, but excess Mg2+ was inhibitory. MgADP inhibited hexokinase II. The addition of salts of monovalent cations increased hexokinase II activity. Al3+ was a strong inhibitor of the enzyme at pH 6.6 but not at the optimum pH (8.2). Citrate and 3-phosphoglycerate activated pea seed hexokinase II at pH 6.6, probably by coordinating with aluminum present as a contaminant in commercial ATP. The properties of hexokinase II are compared with those of the other three hexose kinases obtained from pea seed extracts. The possible role of these enzymes in plant carbohydrate metabolism is discussed.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Clarkson D. T. Effect of aluminum on the uptake and metabolism of phosphorus by barley seedlings. Plant Physiol. 1966 Jan;41(1):165–172. doi: 10.1104/pp.41.1.165. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Purich D. L., Fromm H. J., Rudolph F. B. The hexokinases: kinetic, physical, and regulatory properties. Adv Enzymol Relat Areas Mol Biol. 1973;39:249–326. doi: 10.1002/9780470122846.ch4. [DOI] [PubMed] [Google Scholar]
  3. Tornheim K., Gilbert T. R., Lowenstein J. M. Metal contaminants in commercial preparations of nucleotides. Anal Biochem. 1980 Mar 15;103(1):87–93. doi: 10.1016/0003-2697(80)90241-9. [DOI] [PubMed] [Google Scholar]
  4. Turner J. F., Chensee Q. J., Harrison D. D. Glucokinase of pea seeds. Biochim Biophys Acta. 1977 Feb 9;480(2):367–375. doi: 10.1016/0005-2744(77)90029-8. [DOI] [PubMed] [Google Scholar]
  5. Turner J. F., Harrison D. D., Copeland L. Fructokinase (Fraction IV) of Pea Seeds. Plant Physiol. 1977 Nov;60(5):666–669. doi: 10.1104/pp.60.5.666. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Womack F. C., Colowick S. P. Proton-dependent inhibition of yeast and brain hexokinases by aluminum in ATP preparations. Proc Natl Acad Sci U S A. 1979 Oct;76(10):5080–5084. doi: 10.1073/pnas.76.10.5080. [DOI] [PMC free article] [PubMed] [Google Scholar]

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