Résumé
In this study three fluorescent probes were compared, namely the simple Mag-Indo-1, the new ochratoxin A (OTA) and the classical eosin (EOS). Mag-Indo-1 binds to bovine serum albumin (BSA) with a high binding constant (Kd = 1.8 10(-7) M), at a single binding site in an equimolar ratio. Low-specific or multiple binding is not observed. OTA binds to BSA in a 2:1 ratio. The protein shows two identical binding sites (Kd(1) = 1.5 10(-7) M and Kd(2) = 6 10(-7) M) and a fluorescence quenching between the two ligands. EOS binds BSA with very high binding constants (Kd(1) = 4 10(-13) M and Kd, = 1.5 10(-11) M) at two dissimilar sites. The mechanism cannot be anymore depicted by an equilibrium but as the formation of two stable new compounds, BSA(L) and BSA(L)(2), appearing one after the other.