Studies on Soluble Fibrin in Plasma III. N-Terminal Analysis of a Modified Fraction I (Cohn) from Plasmin- and Thrombin-Incubated Plasma

Abstract

Fresh human plasma was incubated with urokinase to the extent that the thrombin clotting time was doubled. The clottable proteins were examined by N-terminal amino acid analysis. Increased amounts of N-terminal aspartic acid, glutamic acid, and alanine were found, whereas N-terminal tyrosine and glycine remained almost constant. Urokinase-treated plasma, saturated with soluble fibrin (by subsequent incubation with traces of thrombin), contained 0.92 μmol of N-terminal glycine per μmol clottable protein, as compared with 0.24 μmol in normal, fibrin-saturated plasma. Thus, increased fibrin solubility probably contributes to the abnormal coagulation of plasmas containing fibrinogen degradation products.

Key Words:

• Blood coagulation
• fibrin
• fibrinogen
• fibrinogen
• degradation products
• fibrinolysis
• N-terminal analysis
• plasma proteins
• thrombin
• urokinase