Two forms of fructose 1,6-bisphosphatase from immature wheat endosperm

Sangwan, R. S. ; Singh, Randhir (1988) Two forms of fructose 1,6-bisphosphatase from immature wheat endosperm Physiologia Plantarum, 73 (1). pp. 21-26. ISSN 0031-9317

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Fructose 1,6-bisphosphatase (-D-fructose 1,6-bisphosphate 1-phosphohydrolase, EC; FBPase) from immature wheat endosperm has been resolved into two forms, FBPase-I and FBPase-II. Their specific activities over crude homogenate increased 47- and 77-fold, respectively, by using ammonium sulfate fractionation, DEAE-cellulose chromatography and gel filtration through Sephadex G-200. The pH optimum was 7.6 for FBPase-I and 8.4 for FBPase-II. The two forms were highly specific for the substrate FBP with Km values of 0.17 and 0.08 mM, respectively, for FBPase-I and FBPase-II at their respective pH optimum and saturating Mg2+ concentration. pH had no effect on the Km value for FBPase-I, but that for FBPase-II increased below optimum pH. Neither of the forms had an absolute requirement for Mg2+, although it was essential for maximum activity. Mg2+ could not be replaced by Cu2+, Ca2+, Ba2+, Co2+ or Ni2+. Sulfhydryl reagents inactivated both FBPase-I and FBPase-II. Of the metabolites, only 6-phosphogluconate was inhibitory with 50% inhibition at 2 and 4 mM for FBPase-I and FBPase-II, respectively.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Endosperm; Fructose 1; 6-bisphosphatase; Triticum Aestivum; Wheat
ID Code:50085
Deposited On:21 Jul 2011 14:41
Last Modified:21 Jul 2011 14:41

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