Fluorescence polarization analysis of antigen determinant peptides of human fibrinogen.

Fluorescamine-labelled human fibrinogen was degraded with trypsin. Using fluorescence detection, the degradation products were fractionated by Sephadex G 50 gel filtration. Fragments of 3000-10 000 molecular weight were isolated for the fluorescence polarization studies. Specific antifibrinogen antibody increased the polarization of the isolated low molecular weight fragments. These results suggest that even the smallest proteolytic fragments of fibrinogen contain antigen determinant sequences. The fluorescence polarization method offers a sensitive and valuable approach for the analysis of the small antigenic peptides of human fibrinogen.