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  Isomerization mechanism of the HcRed fluorescent protein chromophore

Sun, Q., Li, Z., Lan, Z., Pfisterer, C., Doerr, M., Fischer, S., et al. (2012). Isomerization mechanism of the HcRed fluorescent protein chromophore. Physical Chemistry Chemical Physics, 14(32), 11413-11424. doi:10.1039/c2cp41217a.

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 Creators:
Sun, Qiao1, Author
Li, Zhen2, Author
Lan, Zhenggang3, Author              
Pfisterer, Christoph4, Author
Doerr, Markus3, Author              
Fischer, Stefan4, Author
Smith, Sean C.1, Author
Thiel, Walter3, Author              
Affiliations:
1Univ Queensland, Ctr Computat Mol Sci, Australian Inst Bioengn & Nanotechnol, Brisbane, Qld 4072, Australia , ou_persistent22              
2Univ Wollongong, ISEM, Wollongong, NSW 2500, Australia, ou_persistent22              
3Research Department Thiel, Max-Planck-Institut für Kohlenforschung, Max Planck Society, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, DE, ou_1445590              
4Univ Heidelberg, IWR, D-69120 Heidelberg, Germany , ou_persistent22              

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Free keywords: PHOTOINDUCED NONADIABATIC DYNAMICS; ELECTRONIC-STRUCTURE CALCULATIONS; 2ND-ORDER PERTURBATION-THEORY; PHOTOACTIVE YELLOW PROTEIN; DENSITY-FUNCTIONAL THEORY; SEMIEMPIRICAL METHODS; MOLECULAR-DYNAMICS; CRYSTAL-STRUCTURE; PROTON-TRANSFER; STRUCTURAL BASIS
 Abstract: To understand how the protein achieves fluorescence, the isomerization mechanism of the HcRed chromophore is studied both under vacuum and in the solvated red fluorescent protein. Quantum mechanical (QM) and quantum mechanical/molecular mechanical (QM/MM) methods are applied both for the ground and the first excited state. The photoinduced processes in the chromophore mainly involve torsions around the imidazolinone-bridge bond (tau) and the phenoxy-bridge bond (phi). Under vacuum, the isomerization of the cis-trans chromophore essentially proceeds by tau twisting, while the radiationless decay requires phi torsion. By contrast, the isomerization of the cis-trans chromophore in HcRed occurs via simultaneous tau and phi twisting. The protein environment significantly reduces the barrier of this hula twist motion compared with vacuum. The excited-state isomerization barrier via the phi rotation of the cis-coplanar conformer in HcRed is computed to be significantly higher than that of the trans-non-coplanar conformer. This is consistent with the experimental observation that the cis-coplanar-conformation of the chromophore is related to the fluorescent properties of HcRed, while the trans-non-planar conformation is weakly fluorescent or non-fluorescent. Our study shows how the protein modifies the isomerization mechanism, notably by interactions involving the nearby residue Ile197, which keeps the chromophore coplanar and blocks the twisting motion that leads to photoinduced radiationless decay.

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 Dates: 2012-06-18
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1039/c2cp41217a
 Degree: -

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Title: Physical Chemistry Chemical Physics
Source Genre: Journal
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Pages: - Volume / Issue: 14 (32) Sequence Number: - Start / End Page: 11413 - 11424 Identifier: ISSN: 1463-9076
CoNE: https://pure.mpg.de/cone/journals/resource/954925272413_1