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. 1974 Feb;53(2):136–139. doi: 10.1104/pp.53.2.136

Properties of Phosphoribulokinase of Whole Chloroplasts 1

Mordhay Avron a,2, Martin Gibbs a
PMCID: PMC541351  PMID: 16658663

Abstract

The ability of intact spinach (Spinacia oleracea) chloroplast preparations to catalyze CO2 fixation and photophosphorylation was examined. Under conditions optimal for CO2 fixation, only poor photophosphorylation was observed. Conditions optimal for photophosphorylation were found to be highly inhibitory to the CO2-fixing capacity of the intact chloroplast preparation.

A method for following the activity of phosphoribulokinase in the intact chloroplast preparation was developed, and conditions for optimal activity were defined. The enzyme was found to be activated 2- to 4-fold by preillumination with a half-time of less than 15 seconds. Activation was inhibited by magnesium ions and selectively by inhibitors of photosynthetic electron transport. We concluded that activation was due to the effect of a photoproduced reductant in a site preceding ferredoxin in the electron transport chain. The photoactivated state of the enzyme decayed in the dark with a half-time of about 8 minutes.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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