The composition and sequence specificity of Pro-Ala-Lys-OH for the thrombolytic activities of P6A and related oligopeptides Original Research Article

The in vitro and in vivo thrombolytic activities of Ala-Arg-Pro-Ala-Lys-OH, its analogs and the related peptides were assayed. The results indicate that when 5Lys of Ala-Arg-Pro-Ala-Lys-OH is changed into 5Arg, and 3Lys of Pro-Ala-Lys-OH is changed into 3Arg the thrombolytic activities are collapsed; when Pro-Ala-Lys-OH is changed into Ala-Pro-Lys-OH, and Ala-Arg-Pro-Ala-Lys-OH is changed into Ala-Arg-Ala-Pro-Lys-OH the thrombolytic activities are also collapsed; when 5Lys of Ala-Arg-Pro-Ala-Lys-OH is changed into 5nLeu the thrombolytic activities are again collapsed. All of the results indicate that for the thrombolytic activities of Ala-Arg-Pro-Ala-Lys-OH and the related peptides Pro-Ala-Lys-OH exhibits either amino acid composition specificity or sequence specificity. The composition and sequence specificity of Pro-Ala-Lys-OH reflects its rule as the pharmacophore of P6A and the related peptides.