Binding of erucic acid with human serum albumin using a spectroscopic and molecular docking study

Erucic acid (EA) is one of the key fatty acids usually found in canola oil, mustard oil and rapeseed oil. Consumption of EA in primates was found to cause myocardial lipidosis and cardiac steatosis. To have an insight of the effect of EA in humans, we performed in vitro interaction studies of EA with the primary plasma protein, human serum albumin (HSA). Spectroscopic (UV-vis and fluorescence) analysis of the HSA-EA interaction revealed a static mode of quenching with binding constant K_b ∼10⁴ reflecting high affinity of EA for HSA. The negative value of ΔG° for binding of EA to HSA in the fluorescence studies indicates the process to be spontaneous. Thermodynamic signatures of the HSA-EA interaction in the complex reflect dominance of hydrogen bonds. Despite predominance of hydrogen bonds, hydrophobic interactions in the HSA-EA complex were found acting as a contributing factor in the binding of EA to HSA, observed as structural change in the far-UV CD spectra. Förster's resonance energy transfer of the EA-HSA complex revealed a distance of 3.2nm between acceptor molecules (EA) and the donor Trp residue of HSA. To have a deeper insight of the structural dependence of the HSA-EA interaction in the complex, thermodynamic study was supplemented with molecular docking. The molecular docking analysis further highlighted the EA binding in the subdomain IIIA (Sudlow site II) of HSA. The information generated in the study reflects greater pharmacological significance of EA and highlights its importance in the clinical medicine.