The investigation of the binding behavior between ethyl maltol and human serum albumin by multi-spectroscopic methods and molecular docking

This paper was designed to investigate the interaction of ethyl maltol with human serum albumin (HSA) under physiological condition by fluorescence, synchronous fluorescence, three-dimensional fluorescence, Fourier transformation infrared spectra, and molecular docking method. Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of HSA by ethyl maltol was static quenching mechanism. The binding constants of ethyl maltol–HSA complexes were observed to be 2.59, 1.88, 1.54, 1.13 × 104 M−1 at 289, 296, 303 and 310 K, respectively. The thermodynamic parameters, ΔH0 and ΔS0 were calculated to be −28.61 kJ mol−1 and −14.59 J mol−1 K−1. Energy transfer from tryptophan to ethyl maltol occurred by a FRET mechanism, and the donor–acceptor distance (3.04 nm) had been determined according to Förster’s theory. Molecular docking studies revealed that ethyl maltol situated within subdomain IIA (site I) of HSA. Fluorescence displacement experiments also proved the binding sites between ethyl maltol and HSA.

Graphical abstractThe binding mode between ethyl maltol and HSA.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The binding properties of ethyl maltol and HSA was investigated in vitro by biophysical methods. ► Hydrogen bond and van der Waals force played a major role in the binding of ethyl maltol to HSA. ► The displacement experiments revealed that the binding of ethyl maltol to HSA mainly took place in subdomain IIA (site I).