Stereoselective interactions of lactic acid enantiomers with HSA: Spectroscopy and docking application

Lactic acid enantiomers, normally found in fermented food, are absorbed into the blood and interact with plasma carrier protein human serum albumin (HSA). Unveiling the effect on the function and structure of HSA during chiral interaction can give a better understanding of the different distribution activities of the two enantiomers. Multi-spectroscopic methods and molecular modelling techniques are used to study the interactions between lactic acid enantiomers and HSA. Time-resolved and steady-state fluorescence spectra manifest that the fluorescence quenching mechanism is mainly static in type, due to complex formation. Binding interactions, deduced by thermodynamic calculation, agree with the docking prediction. Docking results and kinetic constants represent chiral-recognizing discriminations consistently. The bindings of lactic acid enantiomers lead to some microenvironmental and slight conformational changes of HSA as shown by circular dichroism (CD), synchronous and three-dimensional fluorescence spectra. This investigation may yield useful information about the possible toxicity risk of lactic acid enantiomers to human health.