Binding of sodium houttuyfonate analogues to bovine serum albumin revealed by fluoresence quenching study

The binding reaction of sodium houttuyfonate analogues (SHAs) to bovine serum albumin (BSA) was studied by fluorescence quenching. Both dynamic and static interactions are involved in the quenching process. SHAs with shorter carbon chains are more likely to undergo a predominantly dynamic quench over a static quench. In contrast, SHAs with longer carbon chains act as static quenchers. Quench efficiency is in the order SHA-C8 > SHA-C10 > SHA-C12 ≈ SHA-C14 > SHA-C6. It was also observed that the two tryptophan residues of BSA are accessible to SHAs. Most of the SHAs have two binding sites, except SHA-C12, which has one. Binding of SHAs to BSA is as a result of spontaneous intermolecular interaction at the experimental temperature. We concluded that SHAs bind to and may be transported by BSA.