Unraveling the interaction of bisphenol A with collagen and its effect on conformational and thermal stability

Evidence suggests the association of bisphenol A (BPA) with increased collagen (COL) expression in the devel-opment of fibrosis. Ultraviolet and fluorescence spectra on collagen-BPA interaction showed that 100 ng/ml of BPA initiated loosening of protein backbone through unfolding with exposure of tyrosine residues resulting in an intermediate "Molten Globule" state, which later aggregated with 1 mu g/ml of BPA indicated with an apparent red-shift. Conformational changes with CD and ATR-FTIR showed disappearance of negative band with broad-ening and shifting of peptide carbonyl groups. Light scattering findings with TEM images presented initial dissolution followed by unordered thick fibrillar bundles with 30 mu g/ml BPA. The complex was pH sensitive, with calorimetric thermogram revealing increased thermal stability requiring 83 degrees C to denature. Hydrogen bonds of 2.8 angstrom with hydrophobic interactions of BPA in all grooves of collagen molecule with same pattern and binding energy (-4.1 to-3.9 kcal/mol) confirmed the intensity of aggregate formation via in-silico docking.