Uncouplers oxidative phosphorylation

Uncouplers of Oxidative phosphorylation Physiological Uncouplers:-Excessive thyroxine hormone-EFA deficiency-Long chain FA in Brown adipose tissue-Unconjugated hyperbilirubinemia 2, 4 Dinitrophenol: A classic uncoupler of oxidative phosphorylation (mechanism see below). Dicoumarol (Vitamin K analogue): Used as anticoagulant SECTION TWOCalcium: Transpo of Ca++ ion into mitochondria can cause uncoupling. Mitochondrial transpo of Ca++ is energetically coupled to oxidative phosphorylation. It is coupled with uptake of Pi. When Ca++ is transpoed into mitochondria, electron transpo can proceed but energy is required to pump the Ca++ into the mitochondria. Hence, no energy is stored as ATP. CCCP: Chlorocarbonyl cyanide phenylhydrazone-- most active uncoupler. FCCP: Trifluorocarbonyl cyanide phenylhydrazone. As compared to DNP it is hundred times more active as uncoupler.Valinomycin: It produced by a type of Streptomyces. Transpos K+ from the cytosol into matrix and H+ from matrix to cytosol, thereby decreasing the proton gradient.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 146