title: Competitive inhibition of human mitochondrial NADH dehydrogenase by Cibacron Blue F3GA.
abstract: Cibacron Blue F3GA, the chromophore of blue dextran, was tested at 4-16 mumol/l for possible inhibition of NADH dehydrogenase activity when added to mitochondrial preparations from cultured human skin fibroblasts. The free dye was shown to be a competitive inhibitor for NADH in the oxidation of NADH catalyzed by the mitochondrial enzyme. The Ki (5.8 mumol/l) for Cibacron Blue F3GA was considerably lower than the Michaelis constant (Km) found for NADH substrate (13.2-16.1 mumol/l), indicating a strong binding of the dye to the substrate-binding site of the enzyme. This is the first report of the competitive inhibition by Cibacron Blue F3GA of mitochondrial NADH in any species.
mesh_terms: D001667:Binding, Competitive; D004396:Coloring Agents / Q000494:pharmacology*; D003579:Cytochrome Reductases / Q000037:antagonists & inhibitors*; D006801:Humans; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D009245:NADH Dehydrogenase / Q000037:antagonists & inhibitors*; D014227:Triazines / Q000494:pharmacology*
chemical_list: D004396:Coloring Agents; D014227:Triazines; C012842:Cibacron Blue F 3GA; D003579:Cytochrome Reductases; D009245:NADH Dehydrogenase