Are Time-Dependent Fluorescence Shifts at the Tunnel Mouth of Haloalkane Dehalogenase Enzymes Dependent on the Choice of the Chromophore?

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Authors

AMARO Mariana BREZOVSKÝ Jan KOVÁČOVÁ Silvia MAIER Lukáš CHALOUPKOVÁ Radka SYKORA Jan PARUCH Kamil DAMBORSKÝ Jiří HOF Martin

Year of publication 2013
Type Article in Periodical
Magazine / Source Journal of Physical Chemistry B
MU Faculty or unit

Faculty of Science

Citation
Doi http://dx.doi.org/10.1021/jp403708c
Field Genetics and molecular biology
Keywords DYNAMIC STOKES SHIFT; WATER-PROTEIN FLUCTUATIONS; POLAR SOLVATION DYNAMICS; HYDRATION DYNAMICS; DIELECTRIC RESPONSE; SOLVENT RELAXATION; ACTIVE-SITE; SUBSTRATE; SURFACE; SIMULATIONS
Description AB Time-dependent fluorescence shifts (TDFS) of chromophores selectively attached to proteins may give information on the dynamics of the probed protein moieties and their degree of hydration. Previously, we demonstrated that a coumarin dye selectively labeling the tunnel mouth of different haloalkane dehalogenases (HLDs) can distinguish between different widths of tunnel mouth openings. In order to generalize those findings analogous experiments were performed using a different chromophore probing the same region of these enzymes. To this end we synthesized and characterized three new fluorescent probes derived from dimethylaminonaphthalene bearing a linker almost identical to that of the coumarin dye used in our previous study. Labeling efficiencies, acrylamide quenching, fluorescence anisotropies, and TDFS for the examined fluorescent substrates confirm the picture gained from the coumarin studies: the different tunnel mouth opening, predicted by crystal structures, is reflected in the hydration and tunnel mouth dynamics of the investigated HLDs. Comparison of the TDFS reported by the coumarin dye with those obtained with the new dimethylaminonaphthalene dyes shows that the choice of chromophore may strongly influence the recorded TDFS characteristics. The intrinsic design of our labeling strategy and the variation of the linker length ensure that both dyes probe the identical enzyme region; moreover, the covalently fixed position of the chromophore does not allow for a major relocalization within the HLD structures. Our study shows, for the first time, that TDFS may strongly depend on the choice of the chromophore, even though the identical region of a protein is explored.
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