Multispectral and molecular modeling investigations on the binding behaviors of two anticoccidials with serum albumins

Abstract

The interaction properties of monensin/clopidol with bovine/human serum albumin (BSA/HSA) were determined via multispectral together with molecular modeling techniques in the report. Fluorescence quenching spectra at different temperatures and fluorescence lifetime determination demonstrated that the fluorescence quenching belonged to a static quenching type. In the case of monensin-BSA, clopidol-BSA, monensin-HSA and clopidol-HSA, the binding constants K_a (291 K) were 5.42 × 10⁴, 4.96 × 10⁴, 3.22 × 10⁴ and 2.99 × 10⁴ M⁻¹, respectively; the binding distances r₀ were 1.88, 2.53, 2.19 and 2.02 nm, respectively. Monensin and clopidol bound strongly with BSA/HSA with binding free energies equal to −26.37/−25.11 and −26.11/−24.93 kJ mol⁻¹, respectively. The spontaneous binding process was dominated by hydrogen bonds and van der Waals forces as reflected in thermodynamic parameters analyses. Synchronous, CD, FTIR and UV-vis spectra assays confirmed that serum albumins conformations were altered. Using competitive experiment, monensin/clopidol was observed to bind at site I of serum albumins, which were reconfirmed by the results of molecular modeling.

Communicated by Ramaswamy H. Sarma

Keywords:

• Monensin
• clopidol
• serum albumins
• multispectral
• molecular modeling

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This research was supported by Natural Science Foundation Project of Jilin Province Science and Technology Department (No. 20170101020JC).