THE DISTRIBUTION IN HIGHER PLANTS OF TRIPHOSPHOPYRIDINE NUCLEOTIDE-LINKED ENZYME SYSTEMS CAPABLE OF REDUCING GLUTATHIONE

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Abstract
A simple test for glutathione reductase in dialyzed extracts of higher plants is described. Appln. of the test has shown that the enzyme is widely distributed in plant tissues. It was present in soluble form in all of the 15 sources tested: wheat germ, pea seedlings, spinach leaf, sunflower leaf, Sedum spectabile leaf, parsley leaf, tomato leaf, carrot root, sweet potato root, potato tuber, and the fruits of avocado, cantaloupe, and cucumber. After glutathione reductase has been detected in a particular extract, the presence of any other dehydrogenase requiring TPN in that extract may be detd., readily by measurement of the reduction of oxidized glutathione in the presence of TPN and the substrate of the enzyme for which the test is conducted. Further observations on the widespread distribution of malic enzyme and isocitric dehydrogenase have been made with such coupled systems, using the sources listed above. In addition, such a test system has been used to show that the enzyme glucose-6-phosphate dehydrogenase is also widely distributed in the tissues of higher plants. The significance of these findings is discussed.