Effect of certain polypeptides on the biological activities of Measles virus.

The effect of a selected tripeptide, Z-d-Phe-Phe-Arg(NO(2)) (SV-4814) on the kinetics of lysis of green monkey erythrocytes by measles virus hemolysin suggested conditions of competitive inhibition. SV-4814 prevented not only hemoglobin release, but also the preceding leakage of K(+) through the cell membrane. The capacity of 12 different dipeptides, 6 tripeptides, including SV-4814, and 4 tetrapeptides to inhibit measles virus-specific hemolysis and infectivity was analyzed. Tri- and tetrapeptides were more active than dipeptides. The presence of aromatic amino acids and a free carboxyl terminal appeared to be a prerequisite for inhibitory activity. Two compounds, one tripeptide (Z-Phe-d-Phe-d-Tyr) and one tetrapeptide [Z-d-Phe-Arg(NO(2))-d-Met], carried an inhibitory activity, which was about two times higher than that of SV-4814.