Trytophan residue in polymerization site of the carboxyl terminal domain of fibrinogen

Abstract The ‘end-to-end’ association of fibrin was investigated using fragments N-DSKa and D 1 , which represent NH 2 - and COOH-binding domains, respectively. A complex was made by mixing these fragments under neutral to slightly alkaline conditions. The complex was stable and was isolated by gel chromatography. It was, however, dissociated by lowering pH of the buffer solution. Fluorescence derived from tryptophan residues were concomitantly increased but only to a small extent as the dissociation of the complex was induced, indicating that a small number of very specific tryptophan residues play an important role in the binding domain of COOH-terminal region. The modification of only one or two tryptophan residue(s) in fragment D 1 with H 2 O 2 and dioxane indeed abolished its binding to immobilized fragment N-DSKa.