A Proposed Mechanism for the Stimulatory Effect of Bicarbonate Ions on ATP Synthesis in Isolated Chloroplasts
- 1 August 1980
- journal article
- research article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 66 (2), 242-245
- https://doi.org/10.1104/pp.66.2.242
Abstract
The effect of bicarbonate ions on induction of Mg2+-ATPase activity, on the N-ethylmaleimide inhibition of phosphorylation and on energy-dependent adenine nucleotide exchange has been examined with pea (Pisum sativum cv. Laxton''s Progress) seedling chloroplasts. Incubation of chloroplasts with N-ethylmaleimide in the presence of 15 mM bicarbonate in the light results in enhanced inhibition of ATP synthesis when the preillumination pH is maintained between 7.0 and 7.5. Bicarbonate also enhances Mg2+-ATPase activity when it is included in the light-triggering stage at pH 7.0. The conditions (medium pH, bicarbonate concentration, etc.) for demonstrating the bicarbonate-induced enhancement of the N-ethylmaleimide inhibition and ATPase activity are similar to those required for the direct effect of bicarbonate on phosphorylation. Bicarbonate, under the same conditions, does not affect adenine nucleotide exchange (binding or release). The stimulatory effect of bicarbonate on ATP synthesis may be related to its ability to alter directly the conformation of the chloroplast coupling factor under conditions (suboptimal pH) where the enzyme shows minimal activity.This publication has 17 references indexed in Scilit:
- The interactions of coupling ATPases with nucleotidesBiochimica et Biophysica Acta (BBA) - Reviews on Bioenergetics, 1978
- Light-induced exchange of nucleotides into coupling factor 1 in spinach chloroplast thylakoids.Journal of Biological Chemistry, 1976
- Energy‐dependent release of adenine nucleotides tightly bound to chloroplast coupling factor CF1FEBS Letters, 1976
- Influence of adenine nucleotides on the inhibition of photophosphorylation in spinach chloroplasts by N-ethylmaleimide.Journal of Biological Chemistry, 1975
- On the mechanism of activation of the ATPase in chloroplastsBiochimica et Biophysica Acta (BBA) - Bioenergetics, 1974
- Correlation between a Conformational Change in the Coupling Factor Protein and the High Energy State in ChloroplastsJournal of Biological Chemistry, 1972
- Light-dependent Inhibition of Photophosphorylation by N-EthylmaleimideJournal of Biological Chemistry, 1972
- An energy-linked conformational change in the coupling factor in chloroplasts. Studies with hydrogen exchange.1971
- PARTIAL RESOLUTION OF ENZYMES CATALYZING PHOTOPHOSPHORYLATION .3. ACTIVATION OF ADENOSINE TRIPHOSPHATASE AND 32P-LABELED ORTHOPHOSPHATE-ADENOSINE TRIPHOSPHATE EXCHANGE IN CHLOROPLASTS1968
- The Enhancement of Photophosphorylation and the Hill Reaction by Carbon DioxideJournal of Biological Chemistry, 1964