Correlation of structural and functional thermal stability of the integral membrane protein Na,K-ATPase
Miles, Andrew J. and Wallace, Bonnie A. and Esmann, M. (2011) Correlation of structural and functional thermal stability of the integral membrane protein Na,K-ATPase. Biochimica et Biophysica Acta (BBA) - Biomembranes 1808 (10), pp. 2573-2580. ISSN 0006-3002.
The membrane-bound cation-transporting P-type Na,K-ATPase isolated from pig kidney membranes is much more resistant towards thermal inactivation than the almost identical membrane-bound Na,K-ATPase isolated from shark rectal gland membranes. The loss of enzymatic activity is correlated well with changes in protein structure as determined using synchrotron radiation circular dichroism (SRCD) spectroscopy. The enzymatic activity is lost at a 12 °C higher temperature for pig enzyme than for shark enzyme, and the major changes in protein secondary structure also occur at Tm´s that are ~ 10-15 °C higher for the pig than for the shark enzyme. The temperature optimum for the rate of hydrolysis of ATP is about 42 °C for shark and about 57 °C for pig, both of which are close to the temperatures for onset of thermal unfolding. These results suggest that the active site region may be amongst the earliest parts of the structure to unfold. Detergent-solubilised Na,K-ATPases from the two sources show the similar differences in thermal stability as the membrane-bound species, but inactivation occurs at a lower temperature for both, and may reflect the stabilizing effect of a bilayer versus a micellar environment.
|Keyword(s) / Subject(s):||Synchrotron radiation circular dichroism (SRCD) spectroscopy, Na,K-ATPase, membrane protein, thermal melt curves, enzyme activity measurements|
|School:||Birkbeck Schools and Departments > School of Science > Biological Sciences|
|Research Centre:||Bioinformatics, Bloomsbury Centre for, Structural Molecular Biology, Institute of (ISMB)|
|Date Deposited:||22 Jun 2011 09:44|
|Last Modified:||07 Dec 2016 15:05|
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