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

Abstract

Purified fibrinogen and fibrin, and the clottable proteins of normal plasma, have been examined by quantitative N-terminal amino acid analysis. When normal plasma was incubated with traces of thrombin, the clottable proteins always contained N-terminal glycine. This probably reflects soluble fibrin (precipitated by 8% ethanol) and possibly also high molecular weight derivatives of fibrinogen, devoided of fibrinopeptides (precipitated by 16% ethanol). The clottable proteins of normal, non-incubated plasma, did not contain N-terminal glycine, indicating absence of fibrin.

Key Words:

• Blood coagulation
• fibrin
• fibrinogen
• N-terminal analysis
• plasma proteins
• thrombin