Inhibition by N‐ethylmaleimide of the MgATP‐driven proton pump of the chromaffin granules

FEBS Letters

Husebye, Eystein¹  Flatmark, Torgeir¹  Vik Berge, Sissel¹  Grønberg, Martin¹ 

[1] Department of Biochemistry, University of Bergen, Årstadveien 19, 5000 Bergen, Norway

关键词: Proton pump;    Proton channel;    H+-ATPase;    Chromaffin granules;    N-ethylmaleimide;    Adrenal medulla;    ANS;    1-anilinonaphthalene 8-sulphonic acid;    BES;    N;    N-bis(2-hydroxyethyl)-2-amino-ethanesulfonic acid;    DCCD;    N;    N'-dicyclohexylcarbodiimide;    FCCP;    carbonylcyanide-p-trifluoromethoxyphenylhydrazon;    →H+;    quantity of acid equivalents translocated inwards;    NEM;    N-ethylmaleimide;    ΔpH;    pH difference across the membrane;    PIPES;    piperazine-N;    N-bis-2-ethanesulphonic acid;    Δψ;    transmembrane potential;   

DOI  :  10.1016/0014-5793(82)81074-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The thiol reagent N-ethylmaleimide (NEM) completely inhibits the proton pump activity of the H⁺-ATPase in chromaffin granule ‘ghosts’ at concentrations which only partly (∼20%) inhibit the Mg²⁺-dependent ATP hydrolysis. Half-maximal inhibition was obtained at ∼13 μM NEM as compared to 18 μM for the classical proton channel inhibitor N,N'-dicyclohexylcarbodiimide (DCCD), and the apparent stoichiometry of the inhibitors at complete inhibition was NEM:DCCD ⋍ 1 : 2. High concentrations of NEM (⪢100 μM) induce a dissipation of the transmembrane potential generated by MgATP. These findings establish NEM as a valuable proton channel inhibitor in chromaffin granules and explain the rather complex effect of NEM previously reported for catecholamine accumulation in this organelle.

【 授权许可】

Unknown