Effect of pH on CO recombination to cytochrome oxidase in intact mitochondria

FEBS Letters

Stringer, B.K.¹  Harmon, H.James¹ 

[1] Department of Physics and Department of Zoology, Oklahoma State University, Stillwater, OK 74078, USA

关键词: Cytochrome oxidase;    Copper;    CO recombination;    pH;    proton;   

DOI  :  10.1016/0014-5793(90)80315-A

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The rate of recombination of CO with fully reduced cytochrome oxidase in intact beef heart mitochondria was measured after flash photolysis at temperatures between 180 and 230K. At pH 7.4 a single Arrhenius slope corresponds to an apparent energy of activation (E _a) of 10.5 ; the rate constants in 100% CO are twice those in the presence of 1% CO. At pH 5.5 with 100% CO, E _a's of 11.3 and 7.1 are observed above and below 210K, respectively, while E _a's of 7.4 and 11.1 are observed with 1% CO above and below 210K. At pH 9.0 E _a's of 9.2 (above 200K), 12.5 (190–200K), and 2.3 (below 190K) are observed with 1% CO; E _a of 9.4, 13.4, and 2.4 are observed in the same temperature ranges with 100% CO present. The findings support a model with up to 4 energy barriers separating the heme region from the bulk medium with intermediate regions that can hold 1 or 2 CO, depending on pH.

【 授权许可】

Unknown