Temperature dependence of mitochondrial oligomycin-sensitive proton transport ATPase |
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Authors: | G. Solaini A. Baracca G. Parenti Castelli G. Lenaz |
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Affiliation: | (1) Istituto di Chimica Biologica, Università di Bologna, Via Irnerio 48, Italy;(2) Istituto Botanico, Università di Bologna, Via Irnerio 42, Italy |
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Abstract: | The temperature dependence of the oligomycin-sensitive ATPase (complex V) kinetic parameters has been investigated in enzyme preparations of different phospholipid composition. In submitochondrial particles, isolated complex V, and complex V reconstituted in dimirystoyl lecithin vesicles, the Arrhenius plots show discontinuities in the range 18–28°C, while no discontinuity is detected with dioleoyl lecithin recombinant. Van't Hoff plots ofKm also show breaks in the same temperature interval, with the exception of the dioleoylenzyme vesicles, whereKm is unchanged. Thermodynamic analysis of the ATPase reaction shows that DMPC-complex V has rather larger values of activation enthalpy and activation entropy below the transition temperature (24°C) than those of the other preparations, while all enzyme preparations show similar free energies of activation (14.3–18.5 kcal/mol). The results indicate that temperature and lipid composition influence to a different extent both kinetic and thermodynamic parameters of ATP hydrolysis catalyzed by the mitochondrial ATPase. |
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Keywords: | OS-ATPase temperature effect kinetics lipid role membrane enzyme protein-lipid interaction (bovine mitochondria) |
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