Probing the Interaction of Human Serum Albumin with Norfloxacin in the Presence of High-Frequency Electromagnetic Fields: Fluorescence Spectroscopy and Circular Dichroism Investigations

Abstract

The present study describes an investigation by fluorescence quenching, circular dichroism and UV-visible spectroscopy of the interaction between norfloxacin (NRF) and human serum albumin (HSA) in the presence of electromagnetic fields (EMFs). The results obtained from this study indicated that NRF had a strong ability to quench HSA at λex = 280 nm. In addition, a slight blue shift occurred, which suggested that the microenvironment of the protein became more hydrophobic after addition of NRF. The interaction between the NRF and HSA, whether in the absence or presence of an EMF, was considered to be a static quenching mechanism. Moreover, synchronous fluorescence demonstrated that the microenvironment around Trp became modified. Data of HSA-NRF in the presence of EMFs between 1 Hz–1 MHz confirmed the results of quenching and blue shifts. Corresponding Stern-Volmer plots were also drawn and the resultant Ksv and kq values were compared. Moreover, the binding parameters, including the number of binding sites, the binding constant and the distance, r, between donor and acceptor, were calculated based on Förster’s non-radiative energy transfer theory. According to far and near UV-CD, the formation of the complex caused changes of the secondary and tertiary structures of HSA. The obtained results are significant for patients who are subjected to high-frequency radiation as this was found to reduce the affinity of NRF to HSA.

Interaction of cyclic and linear Labaditin peptides with anionic and zwitterionic micelles

“…Therefore, the results give support to propose that the W residues of both peptides are surrounded by a more apolar environment in respect to water solution when in contact with the amphiphilic SDS molecule. This because a k max blue-shift is a fingerprint of changes from polar to apolar medium sensed by W residues [43][44][45][46][47]. In this way, a significant k max blueshift indicates that the W residues, or at least one of them, must be buried in the hydrophobic core of the micelle.…”

Binding of fluphenazine with human serum albumin in the presence of rutin and quercetin: An evaluation of food‐drug interaction by spectroscopic techniques

“…Förster's non‐radiative energy transfer theory is usually used to determine the average distances between amino acid residues and the binding drug . According to Förster's non‐radiative energy transfer theory, energy transfer will happen based on the following conditions: (i) that the donor can produce fluorescence light; (ii) the extent of overlap of the fluorescence emission spectrum of the donor with the absorption spectrum of the acceptor; and (iii) that the acceptor is close enough to the donor, with a maximum distance of 7 nm.…”

“…Hence the degree of binding of drug‐plasma protein determines the availability of drug to the organism. The degree of binding can adjust the concentration of free drugs, extend or shorten the duration of the drugs, and finally influence absorption, distribution, metabolism, and externalization of the drugs . Usually, the drug‐plasma protein interaction can cause interference in the simultaneous binding of drugs because of competition for binding to the same site or due to conformational changes in hydrophobic pockets in the protein .…”

Studies on the interaction of palmatine hydrochloride with bovine hemoglobin

“…Synchronous fluorescence spectra are used to investigate protein conformational change, because it has been shown to give narrow and simple spectra. Synchronous fluorescence spectra of the protein, when Δ λ between the excitation and emission wavelengths was 15 or 60 nm, gave information characteristic of Tyr or Trp residues, respectively . Because the fluorescence emission peak for aromatic Tyr or Trp residues is sensitive to the polarity of its environment, the red shift signifies that fluorescing aromatic residues buried in non‐polar hydrophobic cavities are moved to a more hydrophilic environment; by contrast, the blue shift suggests an increase in hydrophobicity .…”