Interaction between the mitochondrial ATP synthetase and ATPase inhibitor protein

FEBS Letters

Panchenko, Maria V.¹  Vinogradov, Andrei D.¹ 

[1] Department of Biochemistry, School of Biology, Moscow State University, Moscow 119899, USSR

关键词: ATP synthetase Inhibitor protein Acid-base transition Mitochondria;    f1;    beef heart mitochondrial coupling factor;    IF1;    beef heart ATPase protein inhibitor;    AS-particles;    submitochondrial ultrasonic particles depleted of IF1 by slow filtration through Sephadex;    Mops;    3-(N-morpholino)propanesulphonate;    Mes;    4-morpholineethanesulphonate;    FCCP;    carbonyl cyanide p-trifluoromethoxyphenylhydrazone;   

DOI  :  10.1016/0014-5793(85)80611-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The rate of mitochondrial ATPase inactivation by the naturally occurring inhibitor protein in the presence of saturating ATP and Mg²⁺ at pH 8.0 depends hyperbolically on the amount of inhibitor added; the upper limit of an apparent first-order constant for the inactivation process is 1.0⁻¹ at 25°C. A dramatic difference in the inactivation rate is observed when the protein inhibitor is added to the same assay system from either acidic (pH 4.8) or alkaline (pH 8.2) solutions. The slow reversible transition of the inhibitor from its rapidly reacting ‘acidic’ form to the slow reacting ‘alkaline’ form occurs when the solution of the protein inhibitor is subjected to a pH-jump from 4.8 to 8.2 (t ½ ~ 30 s at 25°C). The pH-profile of the inhibitor active/inactive equilibrium suggests that a group with pK _a ~ 6.5 is involved in the transition. Treatment of the inhibitor protein with a histidine-specific reagent (e.g. diethyl pyrocarbonate) abolishes its inactivating effect on the ATPase activity. It is concluded that the protonation/deprotonation of the inhibitor protein followed by its slow conformational changes is the rate-limiting step in the inhibitor-ATP synthetase interaction.

【 授权许可】

Unknown