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Effect of Oxidized Nucleotide Coenzymes and Mercaptoethanol on Stabilization of Plant Dehydrogenase Activity in Crude Extracts



Activity loss of 6-phosphogluconate, glucose-6-phosphate, and glyceraldehyde-3-phosphate dehydrogenases occurs in crude plant extracts prepared with insoluble polyvinylpyrrolidone (PVP) and a reducing agent, such as mercaptoethanol. Oxidized nucleotide coenzymes (1 mM), in addition to mercaptoethanol (100 mM), in the extraction buffer stabilizes activity of these dehydrogenases in extracts from both woody and herbaceous plants. PVP and mercaptoethanol alone equally stabilize malate dehydrogenase from most species tested. The mercaptoethanol and coenzyme treatment has proven useful in quantification, purification, and characterization of dehydrogenases in physiological investigations.