Planta

, Volume 145, Issue 4, pp 377–382

Reversible inhibition of the calvin cycle and activation of oxidative pentose phosphate cycle in isolated intact chloroplasts by hydrogen peroxide

Authors

  • Werner M. Kaiser
    • Laboratory of Chemical Biodynamics, Lawrence Berkeley LaboratoryUniversity of California
Article

DOI: 10.1007/BF00388364

Cite this article as:
Kaiser, W.M. Planta (1979) 145: 377. doi:10.1007/BF00388364

Abstract

Hydrogen peroxide (6x10-4 M) causes a 90% inhibition of CO2-fixation in isolated intact chloroplasts. The inhibition is reversed by adding catalase (2500 U/ml) or DTT (10 mM). If hydrogen peroxide is added to a suspension of intact chloroplasts in the light, the incorporation of carbon into hexose- and heptulose bisphosphates and into pentose monophosphates is significantly increased, whereas; carbon incorporation into hexose monophosphates and ribulose 1,5-bisphosphate is decreased. At the same time formation of 6-phosphogluconate is dramatically stimulated, and the level of ATP is increased. All these changes induced by hydrogen peroxide are reversed by addition of catalase or DTT. Additionally, the conversion of [14C]glucose-6-phosphate into different metabolites by lysed chloroplasts in the dark has been studied. In presence of hydrogen peroxide, formation of ribulose-1,5-bisphosphate is inhibited, whereas formation of other bisphosphates,of triose phosphates, and pentose monophosphates is stimulated. Again, DTT has the opposite effect. The release of 14CO2 from added [14C]glucose-6-phosphate by the soluble fraction of lysed chloroplasts via the reactions of oxidative pentose phosphate cycle is completely inhibited by DTT (0.5 mM) and re-activated by comparable concentrations of hydrogen peroxide. These results indicate that hydrogen peroxide interacts with reduced sulfhydryl groups which are involved in the light activation of enzymes of the Calvin cycle at the site of fructose- and sedoheptulose bisphophatase, of phosphoribulokinase, as well as in light-inactivation of oxidative pentose phosphate cycle at the site of glucose-6-phosphate dehydrogenase.

Key words

Chloroplast metabolism Hydrogen peroxide Regulation

Abbreviations

ADPG

ADP-glucose

DHAP

dihydroxyacetone phosphate

DTT

dithiothreitol

FBP

fructose-1,6-bisphosphate

HEPES

N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid

HMP

hexose monophosphates (fructose-6-phosphate, glucose-6-phosphate, glucose-1-phosphate)

6-PGI

6-phosphogluconate

PMP

pentose monophosphates (xylulose-5-phosphate, ribose-5-phosphate, ribulose-5-phosphate)

RuBP

ribulose-1,5-bisphosphate

S7P

sedoheptulose-7-phosphate

SBP

sedoheptulose-1,7-bisphosphate

Copyright information

© Springer-Verlag 1979