Degradation of human fibrinogen by plasmin: isolation and partial characterization of an early degradation product.

The incubation of human fibrinogen with plasmin gives rise to an early degradation product with a molecular weight of 63,000, calculated by polyacrylamide-gel electrophoresis sodium dodecyl sulfate (PAGE-SDS); this product is resistant to the action of the plasmin for short incubation times and represents 1 +/- 0.2% of the original quantity of fibrinogen. The fragment was isolated from the incubated mixture by gel filtration and has a no-identity reaction with fibrinogen fragment D against fibrinogen fragments D antiserum. The reduction gives rise to three polypeptidic chains with molecular weights of 36,000, 17,000 and 10,000 (calculated by PAGE-SDS). Study of the carbohydrate content of these polypeptidic chains from the reduced 63,000 MW fragment indicates that there is only one electrophoretic region which contains periodic acid-Schiff (PAS) positive material. As the 63,000 MW fragment has a reaction against fibrinogen fragment D antiserum and also contains PAS positive material, according to Pepper and co-workers, it can be taken to arise from the HOOC-terminal region of fibrinogen.