Insight into the binding behavior, structure, and thermal stability properties of β-lactoglobulin/Amoxicillin complex in a neutral environment

Antibiotics are extensively used in agriculture and husbandry, thus threatening human health due to their direct exposure to dairy products. Therefore, it is essential to investigate whether milk proteins are unintended carriers of antibiotics. In this research, therefore, we studied the impact of Amoxicillin on the conformation and structural stability of whey protein β-lactoglobulin by using spectroscopic techniques combined with molecular docking and simulation approaches. Further, the thermal stability of the resultant complex was explored. Amoxicillin was observed to effectively quench β-lactoglobulin's intrinsic fluorescence, suggesting that Amoxicillin was successfully bound to the β-lactoglobulin and a stable complex between them was established. The thermodynamic parameters demonstrated that van der Waals forces and hydrogen bonds dominated the spontaneous bonding process. According to circular dichroism (CD) and Fourier transform infrared (FTIR) analyses, the conformational structure of the β-lactoglobulin was altered upon the complexation with Amoxicillin. Further, this interaction significantly enhanced the thermal stability of β-lactoglobulin compared to sole β-lactoglobulin solutions. Molecular docking theoretically showed the preferred binding locus of Amoxicillin within the β-lactoglobulin structure. Molecular dynamics (MD) simulation results further validated the stability of the β-lactoglobulin-Amoxicillin complex. The findings obtained here are helpful for elucidating the potential of β-lactoglobulin to bind and transport harmful substances into the body, thus opening up new avenues for food security.