Electron microscopic studies of plasmic degradation products of fibrinogen. Implications for the disulfide structure of fibrinogen.
Fibrinogen, coagulable plasmic derivatives (Fragments X) and Fragments Y, D and E were studied by negative staining electron microscopy. Fragment X obtained from Stage 1 digests and fibrinogen were both globular, while Fragment X of Stage 2 digests appeared as a nodular filament. The Stage 1 and Stage 2 Fragment X preparations had approximately the same molecular weight, but could be differentiated by several subtle differences in polypeptide chain structure. Fragments Y and D were also filamentous, although shorter than Fragment X (Stage 2), and Fragment E appeared as a small, compact or folded filament. These results agree with the concept that fibrinogen consists of a strand of nodules connected by thin strands, folded into a compact, spherical shape. The molecule opens up when stabilizing bonds are disrupted or liberated by plasmin. The data are compatible with a fibrinogen molecule in which the two halves are linked by a single locus of disulfide bonds at the amino terminus and with the asymmetric hypothesis of plasmic degradation to Fragments X, Y, D and E.
D001665:Binding Sites; D001780:Blood Coagulation Tests; D004220:Disulfides / Q000032:analysis*; D005340:Fibrinogen / Q000032:analysis*; D005341:Fibrinolysin; D006801:Humans; D008854:Microscopy, Electron; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D011487:Protein Conformation
D004220:Disulfides; D010446:Peptide Fragments; D005340:Fibrinogen; D005341:Fibrinolysin