Freshly purified spinach chloroplast fructose bisphosphatase is powerfully inhibited by inorganic phosphate competitively with respect to its substrate fructose 1,6-bisphosphate. The concentrations of phosphate and substrate in the chloroplast stroma are such that the enzyme in this form could not operate at a significant rate in vivo. Incubation of the enzyme with dithiothreitol for 24 h decreases the Km for fructose 1,6-bisphosphate from 0.8 to 0.033 mM, decreases the Km for Mg2+ from 9 to 2 mM and substantially alleviates inhibition by inorganic phosphate. The physiological significance of thiol activation of the enzyme is discussed.
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Research Article| March 01 1980
Properties of freshly purified and thiol-treated spinach chloroplast fructose bisphosphatase
Biochem J (1980) 185 (3): 689–693.
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S A Charles, B Halliwell; Properties of freshly purified and thiol-treated spinach chloroplast fructose bisphosphatase. Biochem J 1 March 1980; 185 (3): 689–693. doi: https://doi.org/10.1042/bj1850689
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