Abstract: This invention relates to novel cyclic compounds linked by a heterocyclic ring system, which are useful as antagonists of the platelet glycoprotein IIb/IIIa complex, to pharmaceutical compositions containing such cyclic compounds, and to methods of using these compounds for the inhibition of platelet aggregation. A representative compound of the invention is cyclo-(D-Val-N(Me)Arg-Gly-Asp-?5-aminomethyl!-2-furoate).

Abstract: A process is provided for cleaving a polypeptide into at least two polypeptide components comprising treating a reduced, free-cysteine form of the polypeptide with a cleaving agent under conditions for cleaving the polypeptide at a desired junction between the polypeptide cleavage products. More preferably, the process for cleaving comprises culturing cells containing DNA encoding said polypeptide, wherein at least one Asp codon is present in said DNA at a desired junction between the components to be cleaved from each other, said culturing resulting in expression of the DNA to produce the polypeptide in the host cell culture; and treating a reduced, free-cysteine form of the polypeptide with dilute acid under conditions for cleaving the polypeptide at the Asp junction.