Evaluation of binding properties of human serum albumin and mono-benzyl phthalate (MBZP): Multi-spectroscopic analysis and computer simulation

Abstract

Mono-benzyl phthalate (MBZP) is the metabolite of benzyl-butyl phthalate (BBP), and it plays a significant role in the toxicity of BBP. In current work, the interaction between MBZP and human serum albumin (HSA) was investigated using solution experiments and computer simulations. The results obtained from experiments illustrated that the intrinsic fluorescence of HSA was quenched because of the formation of HSA–MBZP complex. The Ka value was (8.67 ± 0.34) × 104 M−1 (298 K) and the n value was approximately 1. The formation of HSA–MBZP complex was dominated by H-bonds and van der Waals force. Meanwhile, MBZP was inserted into site I of HSA and enclosed to some amino acid residues. The interaction of Trp-214 with MBZP is an important reason for the fluorescence quenching phenomenon of HSA. The combination of HSA with MBZP could cause the structure of HSA to be more compact and it led to a simultaneous decrease and increase in the α-helix and β-sheet contents, respectively. Additionally, Trp-214 and Arg-218 contributed to stabilising the HSA–MBZP complex, according to the analysis of data from molecular dynamics simulation. In summary, the results could provide new insight into the toxicological study of MBZP.