Intracellular localization of serine acetyltransferase in spinach leaves |
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Authors: | C. Brunold M. Suter |
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Affiliation: | (1) Pflanzenphysiologisches Institut der Universität, Altenbergrain 21, CH-3013 Bern, Switzerland |
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Abstract: | Intact chloroplasts isolated from spinach leaves by a combination of differential and Percoll density gradient centrifugation and free of mitochondrial and peroxisomal contamination contained about 35% of the total leaf serine acetyltransferase (EC 2.3.1.30) activity. No appreciable activity of the enzyme could be detected in the gradient fractions containing broken chloroplasts, mitochondria, and peroxisomes. L-cysteine added to the incubation mixture at 1 mM almost completely inhibited serine acetyltransferase activity, both of leaf and chloroplast extracts. D-cysteine was much less inhibitory. L-cystine up to 5 mM and O-acetyl-L-serine up to 10 mM had no effect on the enzyme activity. When measured at pH 8.4, the enzyme extracted from the leaves had a Km for L-serine of 2.4, the enzyme from the chloroplasts a Km of 2.8 mM.Abbreviations NAS N-acetyl-L-serine - NADP-GPD NADP-dependent glyceraldehyde-3-phosphate dehydrogenase - OAS O-acetyl-L-serine - OASSase O-acetyl-L-serine sulfhydrylase - 3-PGA D-3-phosphoglycerate - SATase serine acetyltransferase |
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Keywords: | Chloroplast (serine acetyltransferase) Cysteine Serine acetyltransferase Spinacia |
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