Insight into the fluorescence quenching of Trp214 at HSA by the Dimetridazole ligand from simulation

Abstract

Please cite this article as: Vladimir A.Pomogaev, Ruslan R.Ramazanov, Kenneth Ruud, Victor Ya.Artyukhov, Insight into the fluorescence quenching of Trp214 at HSA by the Dimetridazole ligand from simulation, Journal of Photochemistry and Photobiology A: Chemistryhttp://dx. Graphical abstractf Highlights Absorption, emission, and fluorescence quenching in various conformers of the dimetridazole and tryptophan residue complex in the binding cavity of Human Serum Albumin (Dmz&Trp214@HSA) were calculated with implementing the two-scale model of MD simulation and various quantum-mechanical approaches in order to generate statistical spectra that are then used for studying the charge transfer processes between the non-bonded Trp214 donor and the Dmz acceptor where types of these intermolecular processes were identified.Spectroscopy is an important tool for detecting drug binding to amino acid sequences. One such important spectroscopic process is the fluorescence quenching due to charge transfer (CT) processes between a drug molecule and the chromophore centre of Human Serum Albumin (HSA). We present a theoretical investigation of the CT occurring upon electronic excitation when a dimetridazole (Dmz) molecule incorporated in HSA interacts with tryptophan residue (Trp214). Structures of the donoracceptor complexes were optimized using density-functional theory in vacuum as well as extracted from molecular dynamics (MD) trajectories of the Dmz and Trp214 complexes in HSA (Dmz&Trp214@HSA). Absorption, emission, and fluorescence quenching of the Trp214&Dmz complex in a large number of MD conformers were calculated using various quantum-mechanical approaches in order to generate statistical spectra that are then used for studying the CT between the non-bonded donor and the acceptor.

Inheritance of Photochromic Properties of Nitro-Substituted and Halogenated Spiropyrans Containing the Pyrrolidino[60]fullerene

“…To reveal the role of the nitro group in photochemical transformations of spyropirans, the low excited states of 5′-aldehyde-substituted 6-nitro-SP (anSP) and both chlorinated and fluorinated 5′-aldehyde-substituted 6-halogenated SP (acSP and afSP, respectively) were calculated along with their 5′-unsubstituted counterparts using the molecular structures optimized in ground states (Table ). In the table CT on these states are represented as isosurfaces of squared MOs differences (sqMOD) rather than electron density difference. ,,, …”

“…To reveal the role of the nitro group in photochemical transformations of spyropirans, the low excited states of 5′-aldehyde-substituted 6-nitro-SP (anSP) and both chlorinated and fluorinated 5′-aldehydesubstituted 6-halogenated SP (acSP and afSP, respectively) were calculated along with their 5′-unsubstituted counterparts using the molecular structures optimized in ground states (Table 1). In the table CT on these states are represented as isosurfaces of squared MOs differences (sqMOD) 58 rather than electron density difference. 22,29,59,60 The aldehyde group predominantly contributes to the energy scheme of the lowest excited states and determines the excitation mechanisms of the lowest singlet and triplet (S aπ and T aπ ) states caused due to CT from n-MO of a lone pair localized on aldehyde group to π*-MO of the indoline fragment (n→π*).…”

Exploring Dyson’s Orbitals and Their Electron Binding Energies for Conceptualizing Excited States from Response Methodology

“…A comparison of the shapes of the DOs obtained in the ground and the excited states can reveal the detail of the orbital relaxation. Thus, the density differences ΔDO k = |ϕ k S n | 2 – |ϕ k S 0 | 2 ( k = π, π*, n O ) between the DOs in the n th excited state ( n = 1, 2) and the ground state provide a visual measure , and the overlap integral ⟨ϕ k S n |ϕ k S 0 ⟩ quantifies the orbital shape variation shown in Figure . In the S 1 state, the most energetically relaxed n O DO (26 a ′) exhibits the smallest overlap (0.808) and the largest visual difference with the S 0 state.…”