Involvement of essential histidine residue(s) in the activity of Ehrlich cell plasma membrane NADH-ferricyanide oxidoreductase.
The existence of histidine residue(s) implicated in the active site of NADH-ferricyanide oxidoreductase in plasma membrane vesicles isolated from Ehrlich ascites tumour cells is investigated. The shape of the pH-dependence curve of the enzyme activity suggests that one or more histidine residues are located at (or near) the active site of the enzyme. This hypothesis is supported by the following experimental data: the loss of activity after treatment with diethyl pyrocarbonate (DEPC) or photooxidation by using Rose bengal, and the strong inhibition caused by Zn2+ ions at micromolar concentrations. The combined arguments support the statement that histidine plays an essential role in the catalytic activity of NADH-ferricyanide oxidoreductase from Ehrlich ascites tumour cells.
Medina
M A
MA
Laboratorio de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Málaga, Spain.
del Castillo-Olivares
A
A
Márquez
J
J
Núñez de Castro
I
I
D000818:Animals; D001665:Binding Sites; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D002712:Chlorides; D004047:Diethyl Pyrocarbonate; D006639:Histidine / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D012395:Rose Bengal; D014407:Tumor Cells, Cultured; D017967:Zinc Compounds
D002712:Chlorides; D017967:Zinc Compounds; D012395:Rose Bengal; D006639:Histidine; C016837:zinc chloride; D009247:NADH, NADPH Oxidoreductases; C014227:ferricyanide reductase; D004047:Diethyl Pyrocarbonate