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Plant Physiology 61:611-616 (1978) © 1978 American Society of Plant Biologists Purification and Kinetics of Higher Plant NADH:Nitrate Reductase 1Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, New York 13210
Squash cotyledon (Cucurbita pepo L.) NADH:nitrate reductase (NR) was purified 150-fold with 50% recovery by a single step procedure based on the affinity of the NR for blue-Sepharose. Blue-Sepharose, which is prepared by direct coupling of Cibacron blue to Sepharose, appears to bind squash NR at the NADH site. The NR can be purified in 2 to 3 hours to a specific activity of 2 µmol of NADH oxidized/minute The kinetic mechanism of higher plant NR was investigated using these highly purified squash and corn NR preparations. Based on initial velocity and product inhibition studies utilizing both enzymes, a two-site ping-pong mechanism is proposed for NR. This kinetic mechanism incorporates the concept of the reduced NR transferring electrons from the NADH site to a physically separated nitrate site.
1 This work was supported in part by a grant from SUNY-University Awards Committee, by a cooperative agreement with Mobil Chemical Company, and by National Science Foundation Grant PCM76-18803. J. S. received a summer support fellowship from the Cottrell Research Grants of the Research Corporation. This article has been cited by other articles:
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