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Plant Physiology 64:187-192 (1979) © 1979 American Society of Plant Biologists Subcellular Localization of the Starch Degradative and Biosynthetic Enzymes of Spinach Leaves 1a Department of Biochemistry and Biophysics, University of California, Davis, California 95616
The subcellular localization of the starch biosynthetic and degradative enzymes of spinach leaves was carried out by measuring the distribution of the enzymes in a crude chloroplast pellet and soluble protein fraction, and by the separation on sucrose density gradients of intact organelles, chloroplasts, peroxisomes, and mitochondria of a protoplast lysate. ADP-Glucose pyrophosphorylase, starch synthase, and starch-branching enzymes are quantitatively associated with the chloroplasts. The starch degradative enzymes amylase, R-enzyme (debranching activity), phosphorylase, and D-enzyme (transglycosylase) are observed both in the chloroplast and soluble protein fractions, the bulk of the degradative enzyme activities reside in the latter fraction. Chromatography of a chloroplast extract on diethylaminoethyl-cellulose resolves the R- and D-enzymes from amylase and phosphorylase activities although the two latter enzyme activities coeluted. The digestion pattern of amylase with amylopectin as a substrate indicates an endolytic activity but displays properties unlike the typical
2 Predoctoral trainee of United States Public Health Service Training Grant GM 119. 1 Supported by the National Science Foundation Grants PCM78-16127 (to J. P.) and PCM76-01495 (administered by P. K. Stumpf).
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