Pyrroline-5-carboxylic acid reductase from soybean leaves |
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Authors: | Patrick M Miler Cecil R Stewart |
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Institution: | Department of Botany and Plant Pathology, Iowa State University, Ames, IA 50011, U.S.A. |
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Abstract: | Pyrroline-5-carboxylic acid reductase was purified 40-fold from soybean leaves (Glycine max L. var Corsoy). The enzyme was fairly unstable, had a broad pH optimum, and was inactivated by heat and acid; NADH and NADPH both served as cofactors. It had a higher activity with NADH (about 4 ×) compared to NADPH, but a lower Km for NADPH. NADP+ inhibited both the NADH- and NADPH-dependent activity. Sulfhydryl group blocking agents reduced the activity as did the carbonyl blocking agent, NH2OH. Thiazolidine-4-carboxylic acid and phosphate inhibited the enzyme and proline inhibited only at high concentrations. ATP, GTP, and CTP were all effective inhibitors of both the NADH- and NADPH-dependent activity. Phosphorylated nucleotide inhibition was reversed by Mg2+ ions. |
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Keywords: | Leguminosae soybean pyrroline-5-carboxylic acid reductase proline |
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