[Protein changes of the erythrocyte membrane during blood preservation].

The present study was conducted on erythrocytes banked in ACD-AG medium for 1, 21, or 42 days at 4 degrees C. Erythrocyte membrane proteins were analysed by means of SDS-polyacrylamide gel electrophoresis in relation to the action of beta-mercaptoethanol. Under banking conditions proteins of the erythrocyte membrane formed 380 000--420 000 daltons aggregates, presumably heterodimers of spectrin I and II, and very high molecular weight aggregates (MG > 600 000 daltons). Part of the aggregated proteins were cross-linked by disulfide bridges, which are subject of the reduction by beta-mercaptoethanol. The nonreducible components were considered an irreversible alteration of the erythrocyte membrane. Many samples of banked erythrocytes exhibited an increase of protein band II.3 (MG = 185 000 daltons) and band IV.2 (MG = 72 000 daltons). The amount of protein band VI (GAPDH) was shown to depend on both banking time and conditions of haemolysis. A modified hypotonic haemolysis with an additional intermediate alkaline incubation of ghosts resulted in a considerable decline of protein band VI of banked erythrocytes. Substraterich incubation of banked erythrocytes, which raised the ATP level well above normal, could only partially restore the membrane bound portion of protein band VI.