Purification from brain of an intrinsic membrane protein fraction enriched in (Na+ + K+)-ATPase.

A microsomal fraction from canine brain gray matter has been extracted with the detergent sodium dodecyl sulfate to partially purify the membrane-bound (Na+ + K+)-stimulated adenosine triphosphatase. Phospholipid, glycolipid, and a family of other glycoproteins are also enriched by the procedure; it is proposed that the product is an intrinsic membrane protein fraction. 6--8-fold purification of (Na+ + K+)-ATPase is obtained without solubilizing the enzyme and without irreversibly altering its turnover number. Final specific activities are 350--400 mumol of ATP hydrolyzed/h per mg protein. The stimulation and reversible inactivation of the (Na+ + K+)-ATPase by dodecyl sulfate were examined for information relevant to the mechanism of action of the detergent.