Temperature-Induced Change in the Ca2+-Dependent ATPase Activity and in the State of the ATPase Protein of Sarcoplasmic Reticulum Membrane
- 1 October 1978
- journal article
- research article
- Published by Oxford University Press (OUP) in The Journal of Biochemistry
- Vol. 84 (4) , 815-821
- https://doi.org/10.1093/oxfordjournals.jbchem.a132193
Abstract
The temperature dependence of the Ca2+-dependent ATPase activity and of the conformational fluctuation of the ATPase molecule has been measured for four kinds of preparations: fragmented sarcoplasmic reticulum, MacLennan's enzyme (purified ATPase preparation), and DOL and egg PC-ATPase (purified ATPase preparations in which lipids are replaced with dioleoyllecithin and egg yolk lecithin, respectively). It has been found that Arrhenius plots of the Ca2+-dependent ATPase activity show a break at about 18°C for all the preparations. Hydrogen–deuterium exchange kinetics of the peptide NH protons were used to measure the conformational fluctuation of the protein molecules. Van't Hoff plots of the conformational fluctuation amplitude of a region near the surface of the ATPase molecule also show a break at about 18°C for all the preparations. It is concluded that the break at around 18°C is not related to a gel-liquid crystalline transition of lipids but to a change in the conformation of the ATPase molecule existing in fluid lipids.Keywords
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