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Binding interaction of a novel fluorophore with serum albumins: steady state fluorescence perturbation and molecular modeling analysis.

Pal U, Pramanik SK, Bhattacharya B, Banerji B, Maiti NC - Springerplus (2015)

Bottom Line: The fluorescence yield of the compound substantially increased inside hydrophobic protein surface and ~30 nm decrease in Stokes' shift, compared to aqueous solution, was observed.Thus, the molecule appears as a new fluorescence probe to report the nature of its binding site in terms of increased fluorescence quantum yield and decreased Stokes' shift.Further it could be useful to detect and study the drug binding site of specific protein of interest.

View Article: PubMed Central - PubMed

Affiliation: Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research (CSIR)-Indian Institute of Chemical Biology (IICB), Kolkata, West Bengal India.

ABSTRACT
Fluorescence emission and anisotropy are widely used to measure the binding parameters and kinetic behavior of reactions that cause a change in the rotational time of a fluorescent molecule. We report here fluorescence emission and anisotropy behavior of a newly synthesized novel naphthalene base fluorophore (methyl 3-[(6-{[2-(tert-butoxy)-2-oxoethyl] (4-methoxyphenyl)amino}naphthalen-2-yl)formamido]propanoate) in several solution conditions including its binding to human and bovine serum albumin proteins both in their native and denatured states. The fluorescence yield of the compound substantially increased inside hydrophobic protein surface and ~30 nm decrease in Stokes' shift, compared to aqueous solution, was observed. Shift in fluorescence excitation peak position from the absorption peak of the molecule was ~8 nm in protein solution. This indicated possible alteration of excited state geometry of the compound by the globular fold of albumins. In addition, we measured the steady state fluorescence anisotropy of the molecule to evaluate several thermodynamic parameters and the results suggested the binding was energetically favorable. The measured ΔG° was ~-30 kJ mol(-1) and the derived dissociation constant was ~10(-6) M. The molecular docking analysis further highlighted the nonspecific association of the compound with the proteins and hydrophobic forces may have a significant role in the binding processes. Under the denatured condition of the protein, the compound lost its binding efficacy and reduction in fluorescence intensity was observed. Thus, the molecule appears as a new fluorescence probe to report the nature of its binding site in terms of increased fluorescence quantum yield and decreased Stokes' shift. It can also report the changes in the binding site due to global change in protein structure such as unfolding/misfolding often linked to several human disorder. Further it could be useful to detect and study the drug binding site of specific protein of interest.

No MeSH data available.


Related in: MedlinePlus

Absorption and fluorescence behavior of compound 5 in the UV–Visible range. Absorption spectrum of compound 5 in 20 mM Tris–HCl buffer of pH 7.4 is shown in blue. Fluorescence emission and excitation spectra of compound 5 are shown in green and yellow, respectively. Compound 5 fluorescence spectra were recorded in the same buffer and normalized against its absorption spectrum
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Fig1: Absorption and fluorescence behavior of compound 5 in the UV–Visible range. Absorption spectrum of compound 5 in 20 mM Tris–HCl buffer of pH 7.4 is shown in blue. Fluorescence emission and excitation spectra of compound 5 are shown in green and yellow, respectively. Compound 5 fluorescence spectra were recorded in the same buffer and normalized against its absorption spectrum

Mentions: In aqueous buffer at pH 7.4, Compound 5 shows a strong absorption band with a peak at 330 nm. Compound 5 is also fluorescence active and the fluorescence band appeared at ~450 nm (Fig. 1). Figure 1 also shows the excitation spectrum of compound 5, which largely overlapped with the absorption spectrum suggesting that excited state conformation of compound 5 in solution is homogeneous and close to ground state structure.Fig. 1


Binding interaction of a novel fluorophore with serum albumins: steady state fluorescence perturbation and molecular modeling analysis.

Pal U, Pramanik SK, Bhattacharya B, Banerji B, Maiti NC - Springerplus (2015)

Absorption and fluorescence behavior of compound 5 in the UV–Visible range. Absorption spectrum of compound 5 in 20 mM Tris–HCl buffer of pH 7.4 is shown in blue. Fluorescence emission and excitation spectra of compound 5 are shown in green and yellow, respectively. Compound 5 fluorescence spectra were recorded in the same buffer and normalized against its absorption spectrum
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4582037&req=5

Fig1: Absorption and fluorescence behavior of compound 5 in the UV–Visible range. Absorption spectrum of compound 5 in 20 mM Tris–HCl buffer of pH 7.4 is shown in blue. Fluorescence emission and excitation spectra of compound 5 are shown in green and yellow, respectively. Compound 5 fluorescence spectra were recorded in the same buffer and normalized against its absorption spectrum
Mentions: In aqueous buffer at pH 7.4, Compound 5 shows a strong absorption band with a peak at 330 nm. Compound 5 is also fluorescence active and the fluorescence band appeared at ~450 nm (Fig. 1). Figure 1 also shows the excitation spectrum of compound 5, which largely overlapped with the absorption spectrum suggesting that excited state conformation of compound 5 in solution is homogeneous and close to ground state structure.Fig. 1

Bottom Line: The fluorescence yield of the compound substantially increased inside hydrophobic protein surface and ~30 nm decrease in Stokes' shift, compared to aqueous solution, was observed.Thus, the molecule appears as a new fluorescence probe to report the nature of its binding site in terms of increased fluorescence quantum yield and decreased Stokes' shift.Further it could be useful to detect and study the drug binding site of specific protein of interest.

View Article: PubMed Central - PubMed

Affiliation: Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research (CSIR)-Indian Institute of Chemical Biology (IICB), Kolkata, West Bengal India.

ABSTRACT
Fluorescence emission and anisotropy are widely used to measure the binding parameters and kinetic behavior of reactions that cause a change in the rotational time of a fluorescent molecule. We report here fluorescence emission and anisotropy behavior of a newly synthesized novel naphthalene base fluorophore (methyl 3-[(6-{[2-(tert-butoxy)-2-oxoethyl] (4-methoxyphenyl)amino}naphthalen-2-yl)formamido]propanoate) in several solution conditions including its binding to human and bovine serum albumin proteins both in their native and denatured states. The fluorescence yield of the compound substantially increased inside hydrophobic protein surface and ~30 nm decrease in Stokes' shift, compared to aqueous solution, was observed. Shift in fluorescence excitation peak position from the absorption peak of the molecule was ~8 nm in protein solution. This indicated possible alteration of excited state geometry of the compound by the globular fold of albumins. In addition, we measured the steady state fluorescence anisotropy of the molecule to evaluate several thermodynamic parameters and the results suggested the binding was energetically favorable. The measured ΔG° was ~-30 kJ mol(-1) and the derived dissociation constant was ~10(-6) M. The molecular docking analysis further highlighted the nonspecific association of the compound with the proteins and hydrophobic forces may have a significant role in the binding processes. Under the denatured condition of the protein, the compound lost its binding efficacy and reduction in fluorescence intensity was observed. Thus, the molecule appears as a new fluorescence probe to report the nature of its binding site in terms of increased fluorescence quantum yield and decreased Stokes' shift. It can also report the changes in the binding site due to global change in protein structure such as unfolding/misfolding often linked to several human disorder. Further it could be useful to detect and study the drug binding site of specific protein of interest.

No MeSH data available.


Related in: MedlinePlus