Plasmic degradation of fibrinogen Paris I.

Abstract

Fibrin obtained from the plasma of a patient having abnormal fibrogen Paris I contains normal alpha, beta, and gamma polypeptide chains as well as an abnormal gamma-chain (gammaParis I) of approximately 51,000 daltons molecular weight. Plasmic digestion of Paris I fibrogen and noncrosslinked fibrin yields both normal and abnormal Fragment D molecules, the latter having a higher negative charge and molecular weight than that liberated from normal fibrinogen and noncorsslinked fibrin. After disulfide bond reduction, an abnormal polypeptide chain of approximately 40,500 +/- 2,000 daltons molecular weight was demonstrated in the Paris I digests by dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. Comparison with the electrophoretic pattern for reduced digests of normal substrates indicates that it is a gamma-chain remnant in the normal Fragment D. Although the carbohydrate content in the gamma-Paris I-chain is slightly higher than that in the normal gamma-chain, as measured by periodic acid-Schiff reagent (PAS) staining intensity, it is concluded that extra carbohydrate does not account for the high molecular weight of the gamma-Paris I-chain since the 40,500 dalton chain does not stain with PAS. Plasma digestion of Paris I crosslinked fibrin yields a large amount of Fragment D in addition to Fragment D-D ("D-dimer") and E molecules, in contrast to a digest of normal crosslinked fibrin, from which only the latter two fragments are formed. This finding suggests that the defect in fibrinogen Paris I derives from an abnormality in the carboxy-terminal region of the gammaParis I-chain, so that in the presence of Factor XIII, these chains are not crosslinked and Fragment D-D molecules are not liberated upon subsequent plasmic degradation. The data provide support for the previous conclusion that a longer than normal polypeptide chain sequence at the carboxy-terminal portion of the gammaParis I-chains accounts for the increased size of these chains relative to the normal gamma-chains and for the abnormal function of the intact fibrinogen Paris I molecule.