Electron-transferring enzymes in the plasma membrane of the Ehrlich ascites tumor cell

The plasma membrane of the Ehrlich ascites tumor cell contains an NADH dehydrogenase. This activity was shown not to be due to contamination by other subcellular membranes. A variety of electron acceptors have been compared as to rate with the following result: ferricyanide greater than cytochrome c...

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Bibliographic Details
Published in:Biochemistry (Easton) 1979-04, Vol.18 (8), p.1525-1530
Main Authors: Kilberg, Michael S, Christensen, Halvor N
Format: Article
Language:English
Subjects:
Animals
Carcinoma, Ehrlich Tumor - enzymology
Cell Membrane - enzymology
Chloromercuribenzoates - pharmacology
Cytochromes - metabolism
Electron Transport
Ethylmaleimide - pharmacology
Kinetics
Mice
NADH, NADPH Oxidoreductases - metabolism
Substrate Specificity
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Summary:The plasma membrane of the Ehrlich ascites tumor cell contains an NADH dehydrogenase. This activity was shown not to be due to contamination by other subcellular membranes. A variety of electron acceptors have been compared as to rate with the following result: ferricyanide greater than cytochrome c greater than cytochrome b5 greater than glyoxylate greater than dichlorophenolindophenol. Oxygen acceptance could not be detected. The optimum assay temperature and pH ranges were 30--40 degrees C and pH 6--8, respectively. With respect to either NADH or ferricyanide, the kinetics yielded linear double-reciprocal plots. Inhibition of the enzyme by sulfhydryl reagents could be blocked by excess NADH. Detergents such as Triton X-100 or cholate resulted in solubilization of the enzymatic activity, but phospholipase A2 did not. The activity differed from that of the mitochondria in that it was not inhibited by rotenone or antimycin A. The possible involvement of NADH oxidation in the energetics of plasma membrane transport is discussed.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00575a021