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Plant Physiology 85:796-800 (1987) © 1987 American Society of Plant Biologists Orientation of Electron Transport Activities in the Membrane of Intact Glyoxysomes Isolated from Castor Bean Endosperm 1Department of Biological Sciences, The George Washington University, Washington, DC 20052
Intact glyoxysomes were isolated from castor bean endosperm on isometric Percoll gradients. The matrix enzyme, malate dehydrogenase, was 80% latent in the intact glyoxysomes. NADH:ferricyanide and NADH:cytochrome c reductase activities were measured in intact and deliberately broken organelles. The latencies of these redox activities were found to be about half the malate dehydrogenase latency. Incubation of intact organelles with trypsin eliminated NADH:cytochrome c reductase activity, but did not affect NADH:ferricyanide reductase activity. NADH oxidase and transhydrogenase activities were negligible in isolated glyoxysomes. Mersalyl and Cibacron blue 3GA were potent inhibitors of NADH:cytochrome c reductase. Quinacrine, Ca2+ and Mg2+ stimulated NADH:cytochrome c reductase activity in intact glyoxysomes. The data suggest that some electron donor sites are on the matrix side and some electron acceptor sites are on the cytosolic side of the membrane.
2 Present address: Plant Photobiology Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, West, Beltsville, MD 20705. 1 Supported by National Science Foundation PCM 8216051. This article has been cited by other articles:
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