Characterization of cytosolic phosphoglucoisomerase from immature wheat (Triticum aestivum L.) endosperm

Sangwan, R. S. ; Singh, Randhir (1989) Characterization of cytosolic phosphoglucoisomerase from immature wheat (Triticum aestivum L.) endosperm Journal of Biosciences, 14 (1). pp. 47-54. ISSN 0250-5991

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Official URL: http://www.ias.ac.in/jarch/jbiosci/14/47-54.pdf

Related URL: http://dx.doi.org/10.1007/BF02703521

Abstract

Phosphoglucoisomerase from cytosol of immature wheat endosperm was purified 650-fold by ammonium sulphate fractionation, isopropyl alcohol precipitation, DEAE-cellulose chromatography and gel filtration through Sepharose CL-6B. The enzyme, with a molecular weight of about 130,000, exhibited maximum activity at pH 8.1. It showed typical hyperbolic kinetics with both fructose 6-P and glucose 6-P with Km of 0.18 mM and 0.44mM respectively. On either side of the optimum pH, the enzyme had lower affinity for the substrates. Using glucose 6-P as the substrate, the equilibrium was reached at 27% fructose 6-P and 73% glucose 6-P with an equilibrium constant of 2.7. The ΔF' calculated from the apparent equilibrium constant was +597 cal mol-1. The activation energy calculated from the Arrhenius plot was 5500 cal mol-1. The enzyme was completely inhibited by ribose 5-P, ribulose 5-P and 6-phosphogluconate, with Ki values of 0.17, 0.25 and 0.14 mM respectively. The probable role of the enzyme in starch biosynthesis is discussed.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Wheat; Triticum aestivum ; Endosperm; Cytosol; Phosphoglucoisomerase
ID Code:50090
Deposited On:21 Jul 2011 14:41
Last Modified:18 May 2016 04:30

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