Sulfhydryl groups are involved in H+ translocation via the uncoupling protein of brown adipose tissue mitochondria

[摘要]

Mersalyl inhibits H⁺ transport via the uncoupling protein (UP) in brown adipose tissue (BAT) mitochondria estimated as swelling in potassium acetate (K _i 67 μM) or as valinomycin-induced H⁺ extrusion in K ₂SO₄ (K _i 55 μM) and KCl. The swelling in KCl is depressed only slightly. Some other SH-reagents (p-hydroxymercuribenzoate, 5,5'-dithiobis(2-nitrobenzoate) and thiolyte DB), but not hydrophobic reagents (N-ethylmaleimide and eosin-5-maleimide), exhibit analogous inhibition. Thus an essential SH-group localized at the water-accessible cytosolic surface of UP was found to be involved in H⁺ transport via UP but not in Cl⁻ transport.

[学科分类] 生物化学/生物物理

[关键词] Mersalyl;Uncoupling protein;Sulfhydryl reagent;H+ transport;Sulfhydryl group;(Brown-fat mitochondria);BAT;brown adipose tissue;BSA;bovine serum albumin;CCCP;carbonyl cyanide m-chlorophenylhydrazone;DCCD;dicyclohexylcar-bodiimide;DTNB;5;5'-dithiobis(2-nitrobenzoate);EMA;eosin-5-maleimide;NEM;N-efhylmaleimide;PMB;p-hydroxymercuribenzoate;TBT;tributyltin chloride;UP;uncoupling protein