NMR studies of pig gastric microsomal H+,K+-ATPase and phospholipid dynamics. Effects of ethanol perturbation.

The effects of ethanol on the gastric H+,K+-ATPase activity and the degree of mobility of various microsomal phospholipids were assessed using 31P and 1H NMR. This illuminated the role of lipid-protein association in the function of pig gastric microsomes. Treatment of gastric microsomes with 15% ethanol for 1 min at 37 degrees C inactivated the H+,K+-ATPase activity, which could largely be reconstituted by supplementation with phosphatidylcholine isolated from the gastric microsomes. Under similar conditions, the 1H NMR profile of the microsomal +N(CH3)3 choline moiety showed dramatic enhancement of peak intensity as well as a break point at 25 degrees C which was restored to the untreated control value after reconstitution. This break, together with the dramatic enhancement in the overall lipid profile, compared to the control and reconstituted microsomes, suggested a greater degree of freedom of movement of the microsomal lipids following ethanol perturbation. The data demonstrate the unique ability that a combined approach using 31P and 1H NMR holds as a noninvasive probe to study the structure-function relationship of biomembranes.