Mechanistic and conformational studies on the interaction of sulfamethazine with human immunoglobulin G by molecular modeling and multi‐spectroscopic approach in vitro

Abstract

Binding interaction of sulfamethazine (SMZ) with human immunoglobulin G (HIgG) has been explored under physiological conditions. The interaction mechanism was firstly predicted through molecular modeling which showed that several hydrogen bonds participated in stabilizing the SMZ-HIgG complex. Fluorescence spectroscopy, ultraviolet-visible (UV-vis) light absorption and circular dichroism (CD) spectroscopy were used to analyze the binding site, binding constants and effects of SMZ on HIgG stability and secondary structure. The binding parameters and thermodynamic parameters at different temperatures for the reaction have been calculated according to the Scatchard, Sips and Van 't Hoff equations, respectively. Experimental results showed that the quenching mechanism was a static quenching and there was one independent class of binding site on HIgG for SMZ during their interaction. The thermodynamic parameters of the reaction, namely standard enthalpy ΔH(0) and entropy ΔS(0), had been calculated to be -19.12 kJ · mol(-1) and 20.22 J · mol(-1) · K(-1), respectively, which meant that the electrostatic interaction was the predominant intermolecular force in stabilizing the SMZ - HIgG complex. Moreover, the conformational changes of HIgG in the presence of SMZ were confirmed by three-dimensional fluorescence spectroscopy, UV-vis absorption spectroscopy and CD spectroscopy.

Molecular docking explores heightened immunogenicity and structural dynamics of acetaldehyde human immunoglobulin G adduct

“…Molecular docking was performed to study the potential binding site of the AA molecule at the F ab and F c fragments of IgG . The specific binding of AA with IgG through hydrogen bonds and hydrophobic interactions are shown in Figures .…”

“…Molecular docking was performed to study the potential binding site of the AA molecule at the F ab and F c fragments of IgG. 16,31 The specific binding of AA with IgG through hydrogen bonds and hydrophobic interactions are shown in Figures 6-8. It is evident from the result that AA forms one hydrogen bond with F ab (heavy chain) and two hydrogen bonds with F c fragment.…”

“…Any alterations in its structure can hinder the function of immunoglobulins and affect its contribution in humoral immunity. 16 The work presented here shows the modification of human IgG with 5 mM AA in presence of reducing agent sodium borohydride. Structural and functional alterations in AA-IgG were detected by various physicochemical techniques.…”

“…Human IgG can serve as a transporter of drugs and plays an important role in the discovery of novel drug delivery systems through targeted drug therapy. Any alterations in its structure can hinder the function of immunoglobulins and affect its contribution in humoral immunity …”

Interactions of Fly Ash Particles with Mucin and Serum Albumin

“…The fluorescence quenching was probably because of the change in the hydrophobic environment for the fluorophore upon the addition of fly ash particles. 31,35 Generally, fluorescence quenching can be divided into static quenching and dynamic quenching (collision quenching).…”