Bovine prothrombin fragment 1, segment 1-10. Synthesis and immunological investigation

The N-terminal decapeptide methyl ester, H-Ala-Asn-Lys-Gly-Phe-Leu-Gla-Gla-Val-Arg-OCH3 (16) of bovine prothrombin fragment 1 has been prepared by standard solution techniques, via a fragment coupling strategy. Hexapeptide Boc-Ala-Asn-Lys epsilon (Boc)-Gly-Phe-Leu-OBzl (9) was obtained by coupling Boc-Ala-Asn-Lys epsilon (Boc)Gly-OH (6) to the trifluoroacetate salt of H-Phe-Leu-OBzl (8). Hydrogenolysis of (9) followed by coupling to HCl. H-Gla gamma (OtBu)2-Gla gamma (OtBu)2-Val-Arg(HCl)-OCH3 (14) gave the fully protected decapeptide (15). Treatment of 15 with 90% trifluoroacetic acid followed by ion exchange chromatography of 15 yielded the methyl ester (16). The decapeptide 16 labeled with 125I using the Bolton-Hunter reagent, did not bind to antibodies specific for the calcium ion-induced conformation of bovine fragment 1.