A molecular sieving method for preparing erythrocyte membranes.

The most widely used methods for preparing erythrocyte membranes are time-consuming, since they involve repeated steps of centrifugation and washing. We have found that membranes can be prepared in a rapid and simple way by molecular-sieve chromatography on a Sepharose 4B column. Two sizes of columns have been used, one 9-ml column to prepare about 1 mg of membrane proteins in 10 min and one 2-litre column for larger amounts (up to 200 mg in 15 min). The optimal pH and phosphate concentration for the separation of hemoglobin from the membranes were found to be 7.5 and 5 mM, respectively. Sodium dodecyl sulphate (SDS) electrophoretic analysis of the membrane proteins prepared by centrifugation and by this new method shows similar protein compositions.