The impact of different geometrical restrictions on the nonadiabatic photoisomerization of biliverdin chromophores

Fang, Yuan; Huang, Haiyi; Lin, Kunni; Xu, Chao; Gu, Feng; Lan, Zhenggang

doi:10.1039/d2cp02941c

Cited by 1 publication

(1 citation statement)

References 62 publications

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“…The Pr-Pfr transformation cycle and its biological activity have been studied extensively. ,− In Pr form, the BV chromophore adopts the ZZZssa conformation (C 5 -Z, C 10 -Z, C 15 -Z, C 5 -syn, C 10 -syn, and C 15 -anti). This conformation exhibits absorption properties within the UV–visible range, revealing two distinct spectral features similar to porphyrin molecules.…”

Section: Introductionmentioning

confidence: 99%

Conformational Effects on the Absorption Spectra of Phytochromes

Santra,

Manna,

Chakrabarty

et al. 2024

J. Phys. Chem. B

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Bacteriophytochrome is a photoreceptor protein that contains the biliverdin (BV) chromophore as its active component. The spectra of BV upon mutation remain remarkably unchanged, as far as spectral positions are concerned. This points toward the minimal effect of electrostatic effects on the electronic structure of the chromophore. However, the relative intensities of the Q and Soret bands of the chromophore change dramatically upon mutation. In this work, we delve into the molecular origin of this unusual intensity modulation. Using extensive classical MD and QM/MM calculations, we show that due to mutation, the conformational population of the chromophore changes significantly. The noncovalent interactions, especially the stacking interactions, lead to extra stabilization of the cyclic form in the D207H mutated species as opposed to the open form in the wild-type BV. Thus, unlike the commonly observed direct electrostatic effect on the spectral shift, in the case of BV the difference observed is in varying intensities, and this in turn is driven by a conformational shift due to enhanced stacking interaction.

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