Fluorimetric probes of the individual and competitive binding of 1-anilinonaphthalene-8-sulfonate, eosine and fluorescene to bovine serum albumin.

ABSTRACT

Fluorescence of 1-anilinonaphthalene-8-sulfonate (ANS) is greatly enhanced on its binding to bovine serum albumin (BSA). Fluorimetric titration shows that three ANS molecules bind per BSA molecule. The enhanced fluorescence of BSA-ANS is quenched by eosine (EOS); and one EOS physically displaces one ANS bound to BSA. The enhanced fluorescence of free ANS in the hydrophobic environment of the nonionic surfactant Triton X 100 is also quenched by EOS but by an energy transfer mechanism. The dye fluorescene (FLSN) also quenches the fluorescence of BSA-bound ANS, but by the energy transfer mechanism. The binding region of ANS in BSA has been speculated.