Plant Physiol. Drug Metab Dispos
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Plant Physiology 57:277-283 (1976)
© 1976 American Society of Plant Biologists

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Web of Science (13)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Heber, U.
Right arrow Articles by Boardman, N. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Heber, U.
Right arrow Articles by Boardman, N. K.
Agricola
Right arrow Articles by Heber, U.
Right arrow Articles by Boardman, N. K.
Articles

Effects of pH and Oxygen on Photosynthetic Reactions of Intact Chloroplasts 1

Ulrich Heber2, T. John Andrews and N. Keith Boardman

Division of Plant Industry, Commonwealth Scientific and Industrial Research Organization, Canberra, Research School of Biological Sciences, Australian National University, Canberra, Australia

Oxygen inhibition of photosynthesis was studied with intact spinach (Spinacia oleracea L.) chloroplasts which exhibited very high rates of photosynthetic CO2 reduction and were insensitive to additions of photosynthetic intermediates when CO2 was available at saturating concentrations. Photosynthetic rates were measured polarographically as O2 evolution, and the extent of the reduction of substrate was estimated from the amount of O2 evolved. With CO2 as substrate, inhibition of photosynthesis by O2 was dependent on pH. At pH values above 8, rates of O2 evolution were strongly inhibited by O2 and only a fraction of the added bicarbonate was reduced before O2 evolution ceased. The extent of O2 evolution declined with increasing O2 concentration and decreasing initial bicarbonate concentration. At pH 7.2, the initial photosynthetic rate was inhibited about 30% at high O2 levels, but the extent of O2 evolution was unaffected and most of the added bicarbonate was reduced. Photosynthetic O2 evolution with 3-phosphoglycerate as substrate was similarly dependent on pH and O2 concentration. In contrast, there was little effect of O2 and pH on oxaloacetate-dependent oxygen evolution. Acid-base shift experiments with osmotically shocked chloroplasts showed that ATP formation was not affected by O2. The results are discussed in terms of a balance between photosynthetic O2 evolution and O2 consumption by the ribulose diphosphate oxygenase reaction.

2 Present address: Institute of Botany, University of Düsseldorf, Germany.

1 This research was supported by CSIRO and the Deutsche Forschungsgemeinschaft (U.H.) and by a Queen's Fellowship in Marine Science (T.J.A.).






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ASPB Publications PLANT PHYSIOLOGY® THE PLANT CELL
Copyright © 1976 by the American Society of Plant Biologists