Effect of n-butanol on Na+, K+-ATPase.

The effect of n-butanol on the activity of Na+, K+-ATPase has been found different at different temperatures. Below the phase-transition temperature, n-butanol has a stimulating effect provided the concentration is not higher than 0.3 M. But if the activity is determined above the phase-transition temperature, n-butanol has an inhibitory effect. The p-nitrophenyl phosphatase activity has been found to be inhibited by n-butanol even at comparatively low temperatures. This is in accord with the finding that the Arrhenius plot for p-nitrophenyl phosphatase did not show any break. It is suggested that at lower temperatures the conformational change involved in the transport of Na+, K+ ions may be the rate-limiting factor in the overall reaction, and n-butanol may be used as a probe for perturbation of the membrane to elucidate the mechanism of Na+, K+-ATPase.