FLUOROMETRIC PROBES OF THE INDIVIDUAL AND COMPETITIVE-BINDING OF 1-ANILINONAPHTHALENE-8-SULFONATE, EOSIN AND FLUORESCEINE TO BOVINE SERUM-ALBUMIN

Fluorescence of 1-anilinonaphthalene-8-sulfonate (ANS) is greatly enha nced on its binding to bovine serum albumin (BSA). Fluorimetric titrat ion shows that three ANS molecules bind per BSA molecule. The enhanced fluorescence of BSA-ANS is quenched by eosine (EOS); and one EOS quen ches the fluorescence of three ANS bound to BSA. Results of equilibriu m dialysis show that 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 b y an energy transfer mechanism. The dye fluoresceine (FLSN) also quenc hes the fluorescence of BSA-bound ANS, but by the energy transfer mech anism. The binding region of ANS in BSA has been speculated.