Probing the Molecular Interaction of Triazole Fungicides
with Human Serum Albumin by Multispectroscopic Techniques and Molecular
Modeling
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Abstract
Triazole fungicides, one category
of broad-spectrum fungicides,
are widely applied in agriculture and medicine. The extensive use
leads to many residues and casts potential detrimental effects on
aquatic ecosystems and human health. After exposure of the human body,
triazole fungicides may penetrate into the bloodstream and interact
with plasma proteins. Whether they could have an impact on the structure
and function of proteins is still poorly understood. By using multispectroscopic
techniques and molecular modeling, the interaction of several typical
triazole fungicides with human serum albumin (HSA), the major plasma
protein, was investigated. The steady-state and time-resolved fluorescence
spectra manifested that static type, due to complex formation, was
the dominant mechanism for fluorescence quenching. Structurally related
binding modes speculated by thermodynamic parameters agreed with the
prediction of molecular modeling. For triadimefon, hydrogen bonding
with Arg-218 and Arg-222 played an important role, whereas for imazalil,
myclobutanil, and penconazole, the binding process was mainly contributed
by hydrophobic and electrostatic interactions. Via alterations in
three-dimensional fluorescence and circular dichroism spectral properties,
it was concluded that triazoles could induce slight conformational
and some microenvironmental changes of HSA. It is anticipated that
these data can provide some information for possible toxicity risk
of triazole fungicides to human health and be helpful in reinforcing
the supervision of food safety