Biochemical Properties of Bound-Ca(2+) in Fibrinolytic Principle (FP) Separated from Agkistrodon acutus Venom.

It has been determined that each FP molecular contains one Ca(2+)-binding site. By the use of fluorescence probe Tb(3+), the distance between Tb(3+) and tryptophan (Trp) residue was obtained to be 0.375. Tb(3+) ion is coordinated with FP more strongly than Ca(2+) ion, and can bind to FP and replace the Ca(2+) ion in FP completely.

Fluorescence Analysis of the Fibrinolytic Principle (FP) from Agkistrodon acutus Venom.

The conformation and the properties of the fibrinolytic principle (FP) from Agkistrodon acutus venom were studied by chemical modification and fluorescence spectroscopy. Results showed that there are more than one tryptophan (Trp) residue in the FP molecule and they are located in the more hydrophobic core, could be quenched by acrylamide (Acr), a polarized quencher without electric charge. The collisional quenching constants of FP at different concentrations of Acr were calculated in terms of Stern-Volmer equation, and the fraction of the Trp quenched was obtained by the modified Stern-Volmer equation as 83%.