Nitrate reductase activity of plasma membranes from cultured carrot cells |
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Authors: | R Barr M Böttger F L Crane D J Morré |
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Institution: | (1) Department of Biological Sciences, Lilly Hall of Life Sciences, Purdue University, 47907-1392 West Lafayette, IN, USA;(2) Institut für Allgemeine Botanik und Botanischer Garten, Universität Hamburg, Hamburg;(3) Department of Medicinal Chemistry and Pharmacognosy, Purdue University, West Lafayette, Indiana |
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Abstract: | Summary Cultured carrot cells (Daucus carota L.) reduced nitrate to nitrite at a slow rate (0.4 moles/g dry wt · h) without any additions to the reaction medium. This rate was doubled or tripled in presence of 100 M NADH. Ethanol and other alcohols stimulated the basal rate 8–10-fold. Isolated carrot plasma membranes also reduced nitrate to nitrite at a rate of 80 nmoles/mg protein · h. This plasma membrane-bound nitrate reductase activity was estimated to be 1.7% of the total activity. Nitrate reduction by carrot cells was inhibited 56% by sodium tungstate, 57% by potassium cyanide, and 87% by gold chloride. It was stimulated by plasma membrane electron transport inhibitors (retinoic acid and chloroquine) and ATPase inhibitors (diethylstilbestrol). From differential effects of some stimulators or inhibitors in the presence or absence of NADH, it can be implied that the nitrate reductase activity of cultured carrot cells was due to a transmembrane enzyme exhibiting an exogenous nitrate reductase activity when NADH was added.Abbreviation DMSO
dimethyl sulfoxide
- SHAM
salicyl hydroxamic acid |
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Keywords: | Carrot cells Nitrate reductase activity Plasma membrane |
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