Regulation of starch biosynthesis in plant leaves: activation and inhibition of ADPglucose pyrophosphorylase

Sanwal, G.G. and Greenberg, E. and Hardie, J. and Cameron, E.C. and Preiss, J. (1968) Regulation of starch biosynthesis in plant leaves: activation and inhibition of ADPglucose pyrophosphorylase. Plant Physiology, 43 (3). pp. 417-427.

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Abstract

The ADPglucose pyrophosphorylases of 7 plant-leaf tissues were partially purified and characterized. In all cases the enzymes showed stability to heat treatment at 650 for 5 minutes in the presence of 0.02 M phosphate buffer, pH 7.0. The leaf ADPglucose pyrophosphorylases were activated 5 to 15-fold by 3-phosphoglycerate. Fructose-6-phosphate and fruotose 1, 6-diphosphate stimulated ADPglucose pyrophosphorylase to lesser extents. The AO,5 (conc of activator required to give 50 %o of the observed maximal activation) of 3-phosphoglycerate for the barley enzyme was 7 X 10-6 M while for the sorghum enzyme it was 3.7 X 10-4 M. Inorganic phosphate proved to be an effective inhibitor of ADPglucose synthesis. The 10.5 (conc of inhibitor that gave 50 % inhibition of activity for the various leaf enzymes varied from 2 X 10- M (barley) to 1.9 X 10-4 M (sorghum). This inhibition was reversed or antagonized by the activator 3-phosphoglycerate. These results form the basis for an hypothesis of the regulation of leaf starch biosynthesis.

Item Type:	Article
Author Affiliation:	Department of Biochemistry and Biophysics, University of California, Davis, California 95616, USA
Subjects:	Plant Physiology and Biochemistry > Plant Physiology Plant Physiology and Biochemistry > Biochemistry
Divisions:	Other Crops
Depositing User:	Sandhya Gir
Date Deposited:	11 Nov 2010 15:36
Last Modified:	29 Dec 2010 20:35
Official URL:	www.plantphysiol.org/cgi/reprint/43/3/417.pdf
URI:	http://eprints.icrisat.ac.in/id/eprint/583

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