REDOX ACTIVE SULFHYDRYLS ARE REQUIRED FOR FRUCTOSE 2,6-BISPHOSPHATE ACTIVATION OF PLANT PYROPHOSPHATE FRUCTOSE-6-PHOSPHATE 1-PHOSPHOTRANSFERASE

被引:11
作者
KISS, F [1 ]
WU, MX [1 ]
WONG, JH [1 ]
BALOGH, A [1 ]
BUCHANAN, BB [1 ]
机构
[1] UNIV CALIF BERKELEY,DEPT PLANT BIOL,BERKELEY,CA 94720
基金
美国国家科学基金会;
关键词
D O I
10.1016/0003-9861(91)90487-4
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The classical, α β-subunit form (Q2) of green tomato pyrophosphate fructose-6-phosphate 1-phosphotransferase (PFP, EC 2.7.1.90), a cytosolic enzyme functional in carbohydrate metabolism, was rapidly inactivated on incubation with the oxidant 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB). Analysis of the DTNB-treated sample by a fluorescence procedure revealed that inactivation was accompanied by oxidation of sulfhydryl groups, primarily on the α-subunit. Phosphate metabolites-fructose 2,6-bisphosphate, fructose 1,6-bisphosphate, Pi, and PPi-protected against DTNB inactivation to varying degrees. The Km values for fructose 6-phosphate and PPi were not changed by DTNB treatment, but the capability for activation by fructose 2,6-bisphosphate was severely diminished. The oxidative inactivation of PFP was reversed by dithiothreitol, but not by monothiols (reduced glutathione or β-mercaptoethanol). Reactivation was accompanied by restoration of the ability to undergo activation by fructose 2,6-bisphosphate. The findings suggest that sulfhydryl groups are essential for the activation of PFP by fructose 2,6-bisphosphate and raise the possibility that a reversible change in their redox status can take place under certain conditions. Evidence that this is the case was obtained with a preparation from wheat flour which, in the absence of an added oxidant, required reduction by a dithiol for activation by fructose 2,6-bisphosphate (dithiothreitol and reduced thioredoxin h). © 1991.
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页码:337 / 340
页数:4
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