Hemolytic Activities of Various Phospholipids and Their Relation to the Rate of Transfer between Membranes1

The correlation between hemolytic activities of various phospholipids and their incorporation into membranes was studied. 1. Short chain phosphatidylcholines can be spontaneously transferred between liposome—liposome and between liposome—erythrocyte membrane. The order of the rate of transfer is as follows: C100PC > C120PC ≫ C140PC. These findings indicate that the transfer process may be favored by the short fatty acyl chain of phosphatidylcholines. 2. The transfer of C120PC was observed in the direction from egg yolk PC liposome to egg yolk PC liposome, from C120PC liposome to erythrocyte membrane, from erythrocyte membrane to egg yolk PC liposome, and from erythrocyte membrane to erythrocyte membrane, but not in the direction from egg yolk PC liposome to erythrocyte membrane or from erythrocyte membrane to C160PC liposome. 3. The accumulation of a certain amount of C80PC, C10.0PC, or C12:0PC on the erythrocyte membrane caused hemolysis. The order of rate of hemolysis is C80PC > C10:0PC > C120PC. C8:0PC induced rapid hemolysis only when the concentration was relatively high; 100-200 μM C80PC and 5-10 μM C100PC, C110PC, or C120PC were required for 50% hemolysis. The distribution coefficient of 80PC between membranes and buffer may be small as compared to those of C100PC and C120PC.