Reconstituted mitochondrial transhydrogenase is a transmembrane protein

FEBS Letters

Pennington, Robin M.¹  Fisher, Ronald R.¹ 

[1] Department of Chemistry, University of South Carolina, Columbia, SC 29208, USA

关键词: Transhydrogenase;    NAP-taurine;    Photochemical modification;    Topography;    Proteoliposome;    NAP-taurine;    N-(4-azido-2-nitrophenyl)-2-aminoethylsulfonate;    AcPyAD+;    3-acetylpyridine adenine dinucleotide;   

DOI  :  10.1016/0014-5793(83)80314-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Bovine heart mitochondrial transhydrogenase, a redox-linked proton pump, can be functionally and asymmetrically inserted into liposomes by a cholate-dialysis procedure such that the active site faces the external medium. N-(4-Azido-2-nitrophenyl)-2-aminoethylsulfonate (NAP-taurine), a membrane-impermeant photoprobe, when encapsulated in the vesicles, covalently modified the enzyme and inhibited transhydrogenation between NADPH and the 3-acetylpyridine analog of NAD⁺ (AcPyAD⁺) in a light-dependent manner. External AcPyAD⁺ increased the rate of inactivation several fold, whereas NADPH, NADP⁺, and NADH were without effect. Labelling of the enzyme by intravesicular [³⁵S]NAP-taurine was enhanced by AcPyAD⁺ and NADP⁺, decreased by NADH, and not significantly affected by NADPH. These results indicate that transhydrogenase spans the membrane and that substrate binding alters the conformation of that domain of the enzyme protruding from the inner surface of the membrane.

【 授权许可】

Unknown