The intrinsic fluorescence of human fibrinogen and its fragments D and E

The tryptophan fluorescence of fibrinogen and its final degradation products--fragment D and E--were compared. Fibrinogen and its derivatives exhibit identical emission and excitation spectra. Their fluorescence intensity is influenced to a different extent by pH titration and temperature. Our studies showed that tryptophan residues of core fragments D and E are much more exposed to quenching effects of acrylamide and ions than intact fibrinogen, which may be caused by conformational changes occurring over the domains during plasmin digestion of fibrinogen molecule.