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Long-Term Preservation of Short-Lived Photoproducts of Phytochromes at Room TemperatureKöhler, Lisa, Gärtner, Wolfgang, Matysik, Jörg, Song, Chen Song 28 August 2023 (has links)
Phytochromes (Phys) are biliproteins that regulate light responses
in plants, fungi, and microorganisms through photoconversion
between a dark state and a photoproduct. Thermal
reversion of the photoproduct is an intrinsic property of all
Phys, typically occurring on a timescale of seconds to days.
Despite methodological advances, the structural and spectroscopic
determination of short-lived photoproducts has proven
challenging. We herein present an innovative approach for
photoproduct stabilisation by incorporating the protein into
trehalose glasses (TGs). The resulting Phy–trehalose matrices
were investigated by UV/Vis absorption and solid-state NMR
spectroscopies. Our results demonstrate that the TGs strongly
inhibit thermal reversion of the incorporated Phy proteins for
periods as long as several weeks at room temperature (RT),
during which the proteins fully sustain their native structures
and spectral and biochemical properties. This sample preparation
approach is beneficial for revealing bona fide structure/
function relationships of short-lived photoproducts that are
otherwise not accessible, thus paving the way towards a deeper
molecular understanding of the diversified spectral properties
of Phys. Our results also provide new insights into the molecular
mechanism of trehalose bioprotection.
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Modeling of phytochrome absorption spectraFalklöf, Olle, Durbeej, Bo January 2013 (has links)
Phytochromes constitute one of the six well-characterized families of photosensory proteins in Nature. From the viewpoint of computational modeling, however, phytochromes have been the subject of much fewer studies than most other families of photosensory proteins, which is likely a consequence of relevant high-resolution structural data becoming available only in recent years. In this work, hybrid quantum mechanics/molecular mechanics (QM/MM) methods are used to calculate UV-vis absorption spectra of Deinococcus radiodurans bacteriophytochrome. We investigate how the choice of QM/MM methodology affects the resulting spectra and demonstrate that QM/MM methods can reproduce the experimental absorption maxima of both the Q and Soret bands with an accuracy of about 0.15 eV. Furthermore, we assess how the protein environment influences the intrinsic absorption of the bilin chromophore, with particular focus on the Q band underlying the primary photochemistry of phytochromes.
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