Metabolic regulation in C4 photosynthesis: Phosphoenol pyruvate carboxylase and 3C intermediates of the photosynthetic carbon reduction cycle

Coombs, J. and Baldry, C.W. (1975) Metabolic regulation in C4 photosynthesis: Phosphoenol pyruvate carboxylase and 3C intermediates of the photosynthetic carbon reduction cycle. Planta, 124 (2). pp. 153-158.

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Abstract

The effects of 3C intermediates of the photosynthetic carbon reduction cycle (glyceraldehyde 3-phosphate [G3P], dihydroxyacetone phosphate and 3-phosphoglyceric acid) on the activity of PEP carboxylase from Pennisetum purpureum (a C4 plant) were investigated. Addition of these compounds at >3mM to standard assay mixtures (5mM concentrations of PEP, HCO3- and Mg2+) reduced the observed activity. The extent of inhibition was greater at lower (<5mM) concentration of Mg2+. G3P was the most potent inhibitor. During studies of saturation kinetics with PEP as variable substrate it was found that addition of these 3C compounds at 2mM reduced the sigmoid nature of Michaelis-Menten plots and reduced the value of n obtained from Hill plots from about 3 to near 1. The results are discussed in terms of the possible regulation of C4 photosynthesis by intermediates of the PCR cycle which are easily leaked from chloroplasts

Item Type: Article
Author Affiliation: Tate and Lyle Ltd. Group Research and Development, Reading RG6 2BX, UK
Subjects: Atmosperic Science
Divisions: General
Depositing User: Mr B Krishnamurthy
Date Deposited: 13 Mar 2012 13:45
Last Modified: 13 Mar 2012 13:45
Official URL: http://dx.doi.org/10.1007/BF00384757
URI: http://eprints.icrisat.ac.in/id/eprint/3820

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