Evidence that a collagen-derived nonapeptide is a specific inhibitor of platelet-collagen interaction

The aggregation of platelets by type III collagen is inhibited by the collagen peptide α₁ (III)CB4 and by 3 fragments derived from this peptide. These fragments share a common portion of 9 aminoacids with the sequence Gly-Lys-Hyp-Gly-Glu-Hyp-Gly-Pro-Lys]. This peptide has been synthetized and its ability to prevent the aggregation of platelets has been studied using various inducers. A marked inhibition of the aggregation by type III collagen was observed, and this response was dose related. The effect was much less pronounced when type I collagen was used. Aggregations by ADP, epinephrin, arachidonic acid, ionophore A 23187 were not altered. The inhibition seems then to be specific for collagen and can be associated to the blocking of platelet membrane sites by this nonapeptide.