Calorimetric and spectroscopic binding studies of amoxicillin with human serum albumin

Abstract

Amoxicillin is a common antibiotic drug used for preventing bacterial colonization of urinary and skin infections. The binding of amoxicillin (AX) to human serum albumin (HSA) in sodium phosphate buffer solution at pH 7.4 has been investigated by UV-visible spectroscopy, fluorescence spectroscopy, Förster resonance energy transfer, isothermal titration calorimetry (ITC), circular dichroism (CD) and FTIR spectroscopy. The binding studies using ITC revealed that the interaction is entropy driven rather than enthalpy as the change in enthalpy (DH°) and change in entropy (TDS°) both are positive, indicating the endothermic reaction with low affinity and hydrophobic interaction. UV-visible absorption spectra of HSA are increased upon addition of AX which shows complex formation of HSA-AX. The fluorescence spectra reveal that the AX has an ability to quench the intrinsic fluorescence of HSA tryptophan through a static quenching procedure. The molecular distance r between donor (HSA) and acceptor (AX) was estimated according to Förster theory of nonradiative energy transfer. The CD spectra showed that the a-helix of HSA increases with increasing the amount of AX. The thermal denaturation has been studied by far-UV CD, and it is found that HSA stability is decreased by the complex formation of HSA and AX. The remarkable change in amide I peak position in infrared spectrum after interaction with AX indicated that secondary structure of HSA has been changed.

Conductance Changes in Bovine Serum Albumin Caused by Drug-Binding Triggered Structural Transitions

“…Previous molecular dynamics (MD) and spectroscopic studies have shown that the major driving forces for the interaction between drugs and BSA are electrostatic force and hydrogen bonding. During the binding process, the original hydrogen bonds are disrupted, which uncoiled the α-helices [25,26,31,32].…”

“…Different volumes (30 µL, 60 µL and 90 µL) of the drug solution at a concentration of 2.0 × 10 −5 mol/L were added to 3 mL of BSA, respectively. Next, the protein solutions were left to stand for 5 min to reach dynamic equilibrium [25,26,27].…”

Insights into the interaction of potent antimicrobial chalcone triazole analogs with human serum albumin: spectroscopy and molecular docking approaches

“…Each domain is further divided into two subdomains (A and B) with numerous requisite ligands. 2 Aer the entry of a drug into systemic circulation, it is exposed to serum albumin, leading to the division of the drug into two types: free drug and drug-HSA complexes. This drug-HSA complex formed provides the supply of free drug and extends the duration of the drug's action.…”

Probing the binding selected metal ions and biologically active substances to the antimicrobial peptide LL-37 using DSC, ITC measurements and calculations

“…In the presented work, two complementary techniques, namely differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC), have been employed to study physicochemical properties of the LL-37 peptide. These techniques are generally used for the characterization of the peptides in aqueous solution [12][13][14].…”