TY - JOUR
T1 - Deciphering the binding site and mechanism of new methylene blue with serum albumins
T2 - A multispectroscopic and computational investigation
AU - Manivel, Perumal
AU - Marimuthu, Parthiban
AU - Ilanchelian, Malaichamy
N1 - Copyright © 2023 Elsevier B.V. All rights reserved.
PY - 2023/11/5
Y1 - 2023/11/5
N2 - Herein, the interaction mechanism of new methylene blue (NMB) with human serum albumin (HSA) and bovine serum albumin (BSA) was carefully investigated both experimentally and conceptually, employing experimental and insilico analysis. The steady-state emission spectral studies showed that the emission intensity of HSA and BSA was quenched significantly by NMB. The findings of the Stern-Volmer and double logarithmic plot revealed that the observed emission quenching process was through a static quenching mechanism and the measured binding constant values (K
b) for HSA-NMB and BSA-NMB are 2.766 and 1.187 × 10
5 dm
3 mol
-1 respectively. The time-resolved fluorescence lifetime measurement and UV-vis absorption investigation further verify the complex formation between NMB and HSA/BSA. The assessment of thermodynamic parameters disclosed the binding process was spontaneous driven by hydrogen bonds (H-bond) and van der Waals interactions, which contributed a significant role in the complexation. Moreover, the secondary structural conformation and microenvironment of HSA/BSA were modified in the presence of NMB, as evidenced by circular dichroism and synchronous fluorescence data. Molecular docking study predicted a plausible binding mode of NMB inside the binding pocket of HSA and BSA. These results demonstrated that the stabilized NMB is found at the Subdomain IIA (site I) of both the proteins and the results were correlated well with the competitive binding assay. Additionally, the principal components analysis revealed less variation of docked poses for HSA, while, more dispersed docked poses were observed for the BSA model. This also highlights the effects of docking towards a modeled protein (BSA). Molecular dynamic (MD) simulation based binding free energy (ΔG
mmgbsa) estimation obtained at 298, 303, 308 and 313 K, were in good agreement with our experimental (ΔG
bind) values.
AB - Herein, the interaction mechanism of new methylene blue (NMB) with human serum albumin (HSA) and bovine serum albumin (BSA) was carefully investigated both experimentally and conceptually, employing experimental and insilico analysis. The steady-state emission spectral studies showed that the emission intensity of HSA and BSA was quenched significantly by NMB. The findings of the Stern-Volmer and double logarithmic plot revealed that the observed emission quenching process was through a static quenching mechanism and the measured binding constant values (K
b) for HSA-NMB and BSA-NMB are 2.766 and 1.187 × 10
5 dm
3 mol
-1 respectively. The time-resolved fluorescence lifetime measurement and UV-vis absorption investigation further verify the complex formation between NMB and HSA/BSA. The assessment of thermodynamic parameters disclosed the binding process was spontaneous driven by hydrogen bonds (H-bond) and van der Waals interactions, which contributed a significant role in the complexation. Moreover, the secondary structural conformation and microenvironment of HSA/BSA were modified in the presence of NMB, as evidenced by circular dichroism and synchronous fluorescence data. Molecular docking study predicted a plausible binding mode of NMB inside the binding pocket of HSA and BSA. These results demonstrated that the stabilized NMB is found at the Subdomain IIA (site I) of both the proteins and the results were correlated well with the competitive binding assay. Additionally, the principal components analysis revealed less variation of docked poses for HSA, while, more dispersed docked poses were observed for the BSA model. This also highlights the effects of docking towards a modeled protein (BSA). Molecular dynamic (MD) simulation based binding free energy (ΔG
mmgbsa) estimation obtained at 298, 303, 308 and 313 K, were in good agreement with our experimental (ΔG
bind) values.
KW - Humans
KW - Serum Albumin/chemistry
KW - Molecular Docking Simulation
KW - Protein Binding
KW - Spectrometry, Fluorescence
KW - Binding Sites
KW - Serum Albumin, Human/chemistry
KW - Serum Albumin, Bovine/chemistry
KW - Thermodynamics
KW - Circular Dichroism
U2 - 10.1016/j.saa.2023.122900
DO - 10.1016/j.saa.2023.122900
M3 - Article
C2 - 37244028
SN - 1386-1425
VL - 300
JO - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
JF - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
M1 - 122900
ER -