Progressive exposure of E-neoantigen associated with degradation of crosslinked fibrin by plasmin in vitro.

Fragment E-neoantigen (Eneo) is a specific marker of structural and conformational changes associated with the degradation of fibrinogen and its related proteins. In this study Eneo expression was followed during the plasmin degradation of crosslinked (XL) fibrin in vitro, utilizing double antibody radioimmunoassay. Eneo was progressively exposed as degradation proceeded and its expression was associated with the liberation of high molecular weight fragments from XL-fibrin, their degradation into fragments DD and E, and the partial degradation of fragment E itself. An isolated protein fraction containing early high molecular weight fragments (MW greater than 360 000 d) and a fraction containing fragments YY and DY expressed approximately 170 times and 15 times less Eneo per protein respectively compared to the fragment E standard. XL-fibrin fragment E isolated from 1-hr plasmin digest expressed approximately 8 times less Eneo than fragment E isolated from 24-hr digest, indicating increased exposure of Eneo during fragment E degradation. Eneo expression of this terminal fragment E was comparable to fibrinogen fragment E. As expected, fragment DD had no Eneo immunoreactivity.