Voltammetric measurements of the kinetics of enzymatic reduction of 2, 6-dichlorophenolindophenol in normal and neoplastic hepatocytes using glucose as substrate.
Amperometric methods were used to study reaction kinetics of 2, 6-dichlorophenolindophenol (DCPIP) with NADH in the homogeneous phase. The second-order rate constant of the reaction was calculated to be 2.4 M-1 . s-1 at 37 degrees C. The reoxidation of the reduced form of DCPIP in air-saturated phosphate-buffered saline was found to follow pseudo-first-order reaction kinetics with rate constant of 5.9 X 10(-4) s-1. These data were compared to the reduction of DCPIP in suspensions of normal and neoplastic hepatocytes, in the absence and presence of oxygen. The reduction of DCPIP by intracellular NAD(P)H was shown to follow mixed-type reaction kinetics different from those of the homogeneous phase. From this, the conclusion was drawn that complexes of enzymes transferring electrons to and from NAD(P)H are involved in intracellular reduction of DCPIP.
D000818:Animals; D002733:Chlorophenols / Q000378:metabolism*; D004396:Coloring Agents; D004563:Electrochemistry; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008114:Liver Neoplasms, Experimental / Q000201:enzymology*; D008297:Male; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000494:pharmacology; D011199:Potentiometry; D051381:Rats; D011919:Rats, Inbred Strains
D002733:Chlorophenols; D004396:Coloring Agents; D009243:NAD; D009249:NADP; D005947:Glucose; C032729:2,6-dichlorophenol; D010100:Oxygen