Subunit relationships between fibrinogen and fibrin degradation products

Abstract

Subunit information of the plasmin mediated degradation products of fibrinogen and fibrin has been described. Fragment X was shown to be heterogeneous containing fragments of molecular weights 266,000 and 238,000 seemingly dependant on the degree of lysis of the Bβ chain. The terminal core fragment D is made up of four molecular weight types. Two major MW fractions, Dg and Dp, contain two chains in common, namely D(Aα):MW 12,000 and D(Bα):MW 37,000. The conversion of Dg to Dp is shown to take place late in the digestion process by the removal of 9,000 MW peptide material from one of the chains of Dg. The third chains of Dg and Dp are D(γ)g:MW 33,000 and D(γ)p 24,000, respectively. The core fragment E was shown to contain three chains of MW's 15,000, 12,000 and 10,000. The sequential release of fragments from non-crosslinked (NXL) fibrin is similar to that of fibrinogen, namely “X” → “Y” → D and E, while fibrin with its γ chains crosslinked as γ-γ dimers degrades directly to the major fragments D-dimer and E. In fibrin the crosslinking of the α chains to α polymers ( α X) seems to endow these chains and the fibrin with plasmin resistance and change the plasmin susceptibility of the fibrin chains from the normal α, β and γ sequence. Terminal core fragments E from fibrinogen and fibrin (NXL and TXL) were similar by SDS-gel electrophoresis.