Gibbon fibrinopeptides: identification of a glycine-serine allelism at position B-3.

The fibrinopeptides A and B of the gibbon (an Asian ape) have been characterized and their relation to other primate types examined. An allelic situation was discovered at location B-3; two of the gibbons studied had both glycine and serine at that position, whereas four others were homozygous for glycine.

Isolation, characterization, and location of a donor-acceptor unit from cross-linked fibrin.

The cross-linking systems of bovine and human fibrins were studied by the introduction of a radioactive substitute donor as an inhibitor of fibrin cross-linking, separation of the constituent polypeptide chains after sulfitolysis, and tryptic digestion of the labeled gamma-chains. The information gathered from this approach enabled us to isolate and characterize the complete donor-acceptor unit in tryptic digests of fibrin gamma-gamma cross-linked systems. In both bovine and human fibrin, this kind of cross-linking is accomplished by reciprocal bridging between overlapping carboxy-terminal segments of neighboring gamma-chains.

Identification of the polypeptide chains involved in the cross-linking of fibrin.

The stabilization of fibrin clots by activated factor XIII involves two different sets of cross-linked chains. In one case (type I) two gamma-chains are linked to each other, indicating that gamma-chains have both donor (suitable lysyl-) and acceptor (suitable glutaminyl-) functions. A second system (type II) consists of a gamma-chain linked to an alpha-chain.