Abstract
The fluorescence intensity of tryptophan residues in hen egg-white lysozyme was measured up to 500 ps after the excitation by irradiation pulses at 290 nm. From the time-dependent variation of fluorescence intensity in a wavelength range of 320–370 nm, the energy relaxation in the dynamic Stokes shift was reconstructed as the temporal variation in wavenumber of the estimated fluorescence maximum. The relaxation was approximated by two exponential curves with decay constants of 1.2 and 26.7 ps. To interpret the relaxation, a molecular dynamics simulation of 75 ns was conducted for lysozyme immersed in a water box. From the simulation, the energy relaxation in the electrostatic interactions of each tryptophan residue was evaluated by using a scheme derived from the linear response theory. Dipole–dipole interactions between each of the Trp62 and Trp123 residues and hydration water molecules displayed an energy relaxation similar to that experimentally observed regarding time constants and magnitudes. The side chains of these residues were partly or fully exposed to the solvent. In addition, by inspecting the variation in dipole moments of the hydration water molecules around lysozyme, it was suggested that the observed relaxation could be attributed to the orientational relaxation of hydration water molecules participating in the hydrogen-bond network formed around each of the two tryptophan residues.
| Original language | English |
|---|---|
| Article number | 129406 |
| Journal | Biochimica et Biophysica Acta - General Subjects |
| DOIs | |
| Publication status | Accepted/In press - 2019 Jan 1 |
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Keywords
- Dipole–dipole interaction
- Dynamic stokes shift
- Energy relaxation
- Fluorescence of tryptophan
- Protein hydration
ASJC Scopus subject areas
- Biophysics
- Biochemistry
- Molecular Biology
Cite this
Dipole–dipole interactions between tryptophan side chains and hydration water molecules dominate the observed dynamic stokes shift of lysozyme. / Fukuda, A.; Oroguchi, Tomotaka; Nakasako, Masayoshi.
In: Biochimica et Biophysica Acta - General Subjects, 01.01.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Dipole–dipole interactions between tryptophan side chains and hydration water molecules dominate the observed dynamic stokes shift of lysozyme
AU - Fukuda, A.
AU - Oroguchi, Tomotaka
AU - Nakasako, Masayoshi
PY - 2019/1/1
Y1 - 2019/1/1
N2 - The fluorescence intensity of tryptophan residues in hen egg-white lysozyme was measured up to 500 ps after the excitation by irradiation pulses at 290 nm. From the time-dependent variation of fluorescence intensity in a wavelength range of 320–370 nm, the energy relaxation in the dynamic Stokes shift was reconstructed as the temporal variation in wavenumber of the estimated fluorescence maximum. The relaxation was approximated by two exponential curves with decay constants of 1.2 and 26.7 ps. To interpret the relaxation, a molecular dynamics simulation of 75 ns was conducted for lysozyme immersed in a water box. From the simulation, the energy relaxation in the electrostatic interactions of each tryptophan residue was evaluated by using a scheme derived from the linear response theory. Dipole–dipole interactions between each of the Trp62 and Trp123 residues and hydration water molecules displayed an energy relaxation similar to that experimentally observed regarding time constants and magnitudes. The side chains of these residues were partly or fully exposed to the solvent. In addition, by inspecting the variation in dipole moments of the hydration water molecules around lysozyme, it was suggested that the observed relaxation could be attributed to the orientational relaxation of hydration water molecules participating in the hydrogen-bond network formed around each of the two tryptophan residues.
AB - The fluorescence intensity of tryptophan residues in hen egg-white lysozyme was measured up to 500 ps after the excitation by irradiation pulses at 290 nm. From the time-dependent variation of fluorescence intensity in a wavelength range of 320–370 nm, the energy relaxation in the dynamic Stokes shift was reconstructed as the temporal variation in wavenumber of the estimated fluorescence maximum. The relaxation was approximated by two exponential curves with decay constants of 1.2 and 26.7 ps. To interpret the relaxation, a molecular dynamics simulation of 75 ns was conducted for lysozyme immersed in a water box. From the simulation, the energy relaxation in the electrostatic interactions of each tryptophan residue was evaluated by using a scheme derived from the linear response theory. Dipole–dipole interactions between each of the Trp62 and Trp123 residues and hydration water molecules displayed an energy relaxation similar to that experimentally observed regarding time constants and magnitudes. The side chains of these residues were partly or fully exposed to the solvent. In addition, by inspecting the variation in dipole moments of the hydration water molecules around lysozyme, it was suggested that the observed relaxation could be attributed to the orientational relaxation of hydration water molecules participating in the hydrogen-bond network formed around each of the two tryptophan residues.
KW - Dipole–dipole interaction
KW - Dynamic stokes shift
KW - Energy relaxation
KW - Fluorescence of tryptophan
KW - Protein hydration
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UR - http://www.scopus.com/inward/citedby.url?scp=85070216761&partnerID=8YFLogxK
U2 - 10.1016/j.bbagen.2019.07.015
DO - 10.1016/j.bbagen.2019.07.015
M3 - Article
JO - Biochimica et Biophysica Acta - General Subjects
JF - Biochimica et Biophysica Acta - General Subjects
SN - 0006-3002
M1 - 129406
ER -