Fluorescence Studies of Binding of Dansylglycine and Dicoumarol to Bovine Serum Albumin

Dansylglycine was used as a fluorescent probe to study the binding of dicoumarol to bovine serum albumin (BSA) at pH 7.4. The fluorescence of dansylglycine was greatly enhanced on binding to BSA with a blue shift in wave-length of the emission maximum. Fluorescence data indicated that dansylglycine was bound tightly to one high-affinity binding site with an association constant of (2.6 ± 0.2) x 106 M-1 in addition to several low-affinity secondary sites. The fluorescence of dansylglycine: BSA complex was quenched by the binding of dicoumarol. This indicates a competition for the binding sites between dicoumarol and dansylglycine in favour of dicoumarol. The fluorescence quenching data indicated that BSA had one high - affinity binding site for dicoumarol with an association constant of (1.46 ± 0.03) x 106 M-1. It was concluded that the binding sites for these drugs are located in the hydrophobic region of BSA. Key Words: Bovine Serum albumin, dansylglycine, dicoumarol, hydrophobic sites. Bio-Research Vol.2(1) 2004: 124-131