Multispectroscopic studies on the interaction of maltol, a food additive, with bovine serum albumin

The interaction between maltol, a food additive, and bovine serum albumin (BSA) under simulated physiological conditions was investigated by fluorescence, UV–Vis absorption, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. The results suggested that the fluorescence quenching of BSA by maltol was a static procedure forming a maltol–BSA complex. The positive values of enthalpy change and entropy change indicated that hydrophobic interactions played a predominant role in the interaction of maltol with BSA. The competitive experiments of site markers revealed that the binding of maltol to BSA mainly took place in subdomain IIA (Sudlow site I). The binding distance between maltol and BSA was 3.01 nm based on the Förster theory of non-radioactive energy transfer. Moreover, the results of UV–Vis, synchronous fluorescence, CD and FT-IR spectra demonstrated that the microenvironment and the secondary structure of BSA were changed in the presence of maltol.