Correlation of structural and functional thermal stability of the integral membrane protein Na,K-ATPase

► Na,K-ATPase from pig kidney is thermally more stable than that of shark. ► Na,K-ATPase activity has optimum at 42 °C for shark and 57 °C for pig. ► Synchrotron radiation circular dichroism is used for structure determination. ► Secondary structure is lost at a ~ 12 °C lower temperature for shark than pig. ► Loss of structure correlates well with loss of enzyme activity.