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Light activation of fructose bisphosphatase in isolated spinach chloroplasts and deactivation by hydrogen peroxide

✍ Scribed by Stephen A. Charles; Barry Halliwell

Publisher: Springer-Verlag
Year: 1981
Tongue: English
Weight: 476 KB
Volume: 151
Category: Article
ISSN: 0032-0935
DOI: 10.1007/bf00395175

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✦ Synopsis

Spinach chloroplast fructose bisphosphatase (EC 3.1.3.11.) exists in both oxidised and reduced forms. Only the latter has the kinetic properties that allow it to function at physiological concentrations of fructose 1,6-bisphosphate and Mg 2 +. Illumination of freshly prepared type A chloroplasts causes a conversion of oxidised to reduced enzyme. The rate of this conversion does not limit the rate of CO2 fixation. In the dark the reduced enzyme partially reverts back to the oxidised form. If catalase is omitted from the reaction medium the rate of CO2 fixation by chloroplasts is decreased and seems to be limited by the rate of conversion of the enzyme to the reduced form. The physiological significance of the light dependent generation of dithiol compounds (such as thioredoxin) within chloroplasts is discussed.

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