title: Study of the enantioselective interaction of diclofop and human serum albumin by spectroscopic and molecular modeling approaches in vitro.
abstract: In this contribution, the enantioselective interactions between diclofop (DC) and human serum albumin (HSA) were explored by steady-state and 3D fluorescence, ultraviolet-visible spectroscopy (UV-vis), and molecular modeling. The binding constants between R-DC and HSA were 0.9213 × 10(5), 0.9118 × 10(5), and 0.9009 × 10(5) L · mol(-1) at 293, 303, 313 K, respectively. Moreover, the binding constants of S-DC for HSA were 1.4766 × 10(5), 1.2899 × 10(5), and 1.0882 × 10(5) L · mol(-1) at 293, 303, and 313 K individually. Such consequences markedly implied the binding between DC enantiomers and HSA were enantioselective with higher affinity for S-DC. Steady-state fluorescence study evidenced the formation of DC-HSA complex and there was a single class of binding site on HSA. The thermodynamic parameters (ΔH, ΔS, ΔG) of the reaction clearly indicated that hydrophobic effects and H-bonds contribute to the formation of DC-HSA complex, which was in excellent agreement with molecular simulations. In addition, both site-competitive replacement and molecular modeling suggested that DC enantiomers were located within the binding pocket of Sudlow's site II. Furthermore, the alterations of HSA secondary structure in the presence of DC enantiomers were verified by UV-vis absorption and 3D fluorescence spectroscopy. This study can provide important insight into the enantioselective interaction of physiological protein HSA with chiral aryloxyphenoxy propionate herbicides and gives support to the use of HSA for chiral pesticides ecotoxicology and environmental risk assessment.
authors.affiliation: Department of Applied Chemistry, China Agricultural University, Beijing, P.R. China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.forename: Zhe
authors.initials: Z
authors.lastname: Li
authors.forename: Xinru
authors.initials: X
authors.lastname: Wang
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Shen
authors.forename: Yao
authors.initials: Y
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Yan
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhou
authors.forename: Wentao
authors.initials: W
authors.lastname: Zhu
mesh_terms: D001665:Binding Sites; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D010647:Phenyl Ethers / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D011422:Propionates / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D017433:Protein Structure, Secondary / Q000187:drug effects; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: C529887:2-(4-(2,4-dichlorophenoxy)phenoxy)propionic acid; D010647:Phenyl Ethers; D011422:Propionates; D012709:Serum Albumin
keywords: diclofop; enantioselectivity; fluorescence; human serum albumin; molecular modeling