Activity of proteoliposomes containing cytochrome oxidase in the submitochondrial orientation

[摘要]

Cytochrome-c oxidase proteoliposomes containing internally trapped cytochrome c can turn over on internal or external cytochrome c. At low TMPD levels the internal activity is significantly lower than the external activity as the functional internal cytochrome c is not fully reduced in the steady state. Increasing TMPD concentration increases the internal rate to equal that of the external enzyme. Internal activity results in the accumulation of TMPD⁺. Valinomycin increases this accumulation and subsequently FCCP decreases it. In the presence of excess external cytochrome c, the effects of these ionophores are reversed. The internally-facing enzyme is thus capable of generating a ΔμH⁺ in proteoliposomes as well as in submitochondrial particles.

[学科分类] 生物化学/生物物理

[关键词] Cytochrome oxidase;Proteoliposome;N;N;N′;N′-Tetramethyl-p-phenylenediamine;Cytochrome c;Fatty acid;COV;cytochrome-c oxidase reconstituted proteoliposomes;c-loaded COV;COV containing entrapped cytochrome c;TMPD;N;N;N′;N′-tetramethyl-p-phenylenediamine;DAD;2;3;5;6-tetramethyl-p-phenylenediamine;PMS;phenazine methosulphate;FCCP;carbonylcyanide p-trifluoromethoxyphenylhydrazone