Study on the interactions of trans-resveratrol and curcumin with bovine α-lactalbumin by spectroscopic analysis and molecular docking.
The ability of bovine α-lactalbumin (BLA) as a whey protein to carry curcumin and trans-resveratrol as two natural polyphenolic compounds was investigated by fluorescence quenching measurements and docking studies. Curcumin is the bioactive component of turmeric and trans-resveratrol is abundant in different types of fruits and vegetables. The binding parameters such as binding constants and the number of substantive binding sites have been estimated from the analysis of fluorescence quenching measurements. The differences in affinities of curcumin and trans-resveratrol for BLA were compared. The short Förster's distance (r) between donor (BLA) and acceptor (curcumin and trans-resveratrol) and also the binding constant values demonstrated the strong interaction between these two polyphenolic compounds and BLA. The thermodynamic parameters were obtained from the fluorescence quenching measurements in different temperatures. It can be concluded from the sign and magnitude of ∆H and ∆S that the final ligand-protein complexes were stabilized by hydrogen bonds. The considerable change in microregion of the Trp residues in BLA is observed upon the binding of the trans-resveratrol to BLA by synchronous fluorescence while this conformation alteration was not observed upon interaction with curcumin. It was indicated by docking studies that curcumin come closer to the Trp-118 than to other tryptophans and trans-resveratrol binds in the vicinity of Trp-60 and Trp-104. Docking studies indicated that these two compounds bind to BLA by two hydrogen bonds. The calculated distances between bound ligands and tryptophans obtained by docking studies were in agreement with fluorescence resonance energy transfer results. Therefore, the strong interaction of curcumin and trans-resveratrol with BLA was confirmed by theoretical and experimental studies. These achieved results may be applicable in the milk industry and drug formulation.
Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Gava Zang, Zanjan 45137-66731, Iran. Electronic address: fmohammadi@iasbs.ac.ir.
Fakhrossadat
F
Mohammadi
Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Gava Zang, Zanjan 45137-66731, Iran.
Marzieh
M
Moeeni
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003474:Curcumin / Q000737:chemistry* / Q000378:metabolism*; D006860:Hydrogen Bonding; D007700:Kinetics; D007768:Lactalbumin / Q000378:metabolism*; D008024:Ligands; D008968:Molecular Conformation; D062105:Molecular Docking Simulation; D011485:Protein Binding; D000077185:Resveratrol; D013050:Spectrometry, Fluorescence; D013267:Stilbenes / Q000737:chemistry* / Q000378:metabolism*; D013816:Thermodynamics; D014364:Tryptophan / Q000378:metabolism
D008024:Ligands; D013267:Stilbenes; D014364:Tryptophan; D007768:Lactalbumin; D003474:Curcumin; D000077185:Resveratrol
Alpha-lactalbumin; Curcumin; Fluorescence quenching; Trans-resveratrol