Use of the red-edge excitation effect for investigation of dielectric interactions in biomembranes

Nemkovich, N. A.; Baumann, Wolfram; Kruchenok, Yu. V.; Reis, Heribert; Рубинов, А. Н.

doi:10.1007/bf02676774

Cited by 2 publications

(2 citation statements)

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“…The final system was first equilibrated with velocity rescaling for 60 ps at 50 K and 80 ps at 300 K. Following this initial equilibration, we ran the system for one additional nanosecond at constant temperature ( T = 300 K) and pressure ( P = 0.1 MPa). To achieve full relaxation, the simulation box was entirely flexible for the first 300 ps, whereas for the remainder of the run, only isotropic changes of the box were allowed . Finally, the system was simulated for an additional 10 ns.…”

Section: Methodsmentioning

confidence: 99%

“…We, thus, initially considered the probe ANS, for which there is a structure of its complex with apoMb. This probe is not, however, ideal because its absorption spectrum is complicated by overlapping electronic states . Even if internal conversion from higher-lying states to the lower fluorescent state is faster than solvation dynamics, as has been suggested to be the case in Trp, − an accurate determination of the reorganization energy , based on the steady-state spectra becomes very difficult.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of the Dielectric Response Obtained from Fluorescence Upconversion Measurements and Molecular Dynamics Simulations for Coumarin 153−Apomyoglobin Complexes and Structural Analysis of the Complexes by NMR and Fluorescence Methods

et al. 2010

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We present a comparison of the dielectric response obtained from fluorescence upconversion experiments and from molecular dynamics simulations of the complexes of coumarin 153 with five apomyoglobins (apoMbs): wild-type horse heart (HH-WT) and those of wild-type sperm whale (SW-WT); its two triple mutants, L29F/H64Q/V68F and H64L/V68F/P88A; and its double mutant, L29F/V68L. Comparisons between experimental and simulated solvation relaxation functions, C(t)s, for the wild-type proteins range from very good to excellent. For the three mutants we investigated, however, agreement between experiment and simulation was considerably inferior. Thus, an NMR study of the complex of the HH-WT complex apoMb, and fluorescence energy transfer and anisotropy studies of the five complexes, were performed to investigate the structures upon which the simulations were based. The NMR measurements confirm our earlier conclusions that the C153 lies in the heme pocket of the HH-WT apoMb. For the wild-type complexes, fluorescence energy transfer measurements provide two rise times, suggesting a definite spatial relationship between the two Trp donors and the C153 acceptor. These results confirm the structural integrity of the wild-type complexes and validate the initial structures used for the molecular dynamics simulations. On the other hand, the three mutants provided single exponential rise times for energy transfer, suggesting that the position of the C153 used in the simulations may have been in error or that the C153 is mobile on the time scale of the energy transfer experiment. Fluorescence anisotropy studies also suggest that the double mutant was not structurally intact. Furthermore, examination of these systems demonstrates the sensitivity of C153 to its environment and permits the observation of differences in the heme pockets. These results point to the importance of structural characterization of modified proteins used in studies of the dielectric response and suggest strategies for performing molecular dynamics simulations of modified proteins.

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Section: Methodsmentioning

confidence: 99%