[8] Application of inhibitors and uncouplers for a study of oxidative phosphorylation

doi:10.1016/0076-6879(67)10011-6

Methods in Enzymology

Volume 10, 1967, Pages 48-57

https://doi.org/10.1016/0076-6879(67)10011-6 Get rights and content

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This chapter discusses the application of inhibitors and uncouplers that are useful in the study of oxidative phosphorylation. The various inhibitors and uncouplers may be classified based on the chemical-coupling theory of oxidative phosphorylation, which can be formulated. The chapter discusses the non-site-specific inhibitors (oligomycin and aurovertin), site I-specific inhibitors (Amytal and alkylguanidines), site II-specific inhibitors (n-Heptylquirwline N-oxide and phenylethylbiguanide), site III inhibitors (synthalin), and inhibitor of phosphorylafion of added ADP. Oligomycin is used to inhibit the synthesis of ATP by respiratory-chain oxidative phosphorylation without inhibiting the initial conservation of energy. Aurovertin is used in ethanolie solution, and 0.4 micromole aurovertin per gram protein inhibits oxidative phosphorylation at all sites. As inhibition by Amytal is partially relieved by dinitrophenol, this compound may be classed as an inhibitor of oxidative phosphorylation. The most commonly used uncoupler is 2, 4-dinitrophenol, which affects all phosphorylation sites in the respiratory chain, but has no effect on the substrate-linked phosphorylation. 2,6 -Dinitrophenol acts very similarly to 2, 4-dinitrophenol. The concentrations of 2, 6-dinitrophenol, at different pH's, inducing the maximal ATPase and maximal stimulation of respiration in the absence of ADP and phosphate. Dicoumarol [3, 3'-methylenebis (4-hydroxycoumarin)] is active on all phosphorylating sites of the respiratory chain, and has no effect on the substrate-linked phosphorylation. Arsenate readily uncouples substrate-linked phosphorylations but is relatively ineffective against respiratory-chain phosphorylation. Other uncouplers gramicidin and valinomycin are also discussed.

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[8] Application of inhibitors and uncouplers for a study of oxidative phosphorylation

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