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Plant Physiology 100:352-359 (1992) © 1992 American Society of Plant Biologists Plant Dihydroxyacetone Phosphate Reductases 1Purification, Characterization, and LocalizationDepartment of Biochemistry, Michigan State University, East Lansing, Michigan 48824-1319
A cytosolic form of dihydroxyacetone phosphate (DHAP) reductase was purified 200,000-fold from spinach (Spinacia oleracea L.) leaves to apparent electrophoretic homogeneity. The purification procedure included anion-exchange chromatography, gel filtration, hydrophobic chromatography, and dye-ligand chromatography on Green-A and Red-A agaroses. The enzyme, prepared in an overall yield of 14%, had a final specific activity of about 500 µmol of DHAP reduced min1 mg1 protein, a subunit molecular mass of 38 kD, and a native molecular mass of 75 kD. A chloroplastic isoform of DHAP reductase was separated from the cytosolic form by anion-exchange chromatography and partially purified 56,000-fold to a specific activity of 135 µmol min1 mg1 protein. Antibodies generated in rabbits against the cytosolic form did not cross-react with the chloroplastic isoform. The two reductases were specific for NADH and DHAP. Although they exhibited some dissimilarities, both isoforms were severely inhibited by higher molecular weight fatty acyl coenzyme A esters and phosphohydroxypyruvate and moderately inhibited by nucleotides. In contrast to previous reports, the partially purified chloroplastic enzyme was not stimulated by dithiothreitol or thioredoxin, nor was the purified cytosolic enzyme stimulated by fructose 2,6-bisphosphate. A third DHAP reductase isoform was isolated from spinach leaf peroxisomes that had been prepared by isopycnic sucrose density gradient centrifugation. The peroxisomal DHAP reductase was sensitive to antibodies raised against the cytosolic enzyme and had a slightly smaller subunit molecular weight than the cytosolic isoform.
2 Present address: Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019. 1 This work was supported by two grants from the U.S. Department of Agriculture: Plant Science Center grant 88-3771-3964 and Competitive Program grant 88-37233-4002. This article has been cited by other articles:
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