Excited state reactions in fluorescent proteins

Meech, Stephen R.

doi:10.1039/b820168b

Cited by 292 publications

(353 citation statements)

References 152 publications

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“…44,60,72 Both these dyes and GFP chromophores display a common binding-dependent fluorescence enhancement associated with the suppression of a common double-bond photoisomerization chemistry in the excited state. [4][5][6][7][73][74][75] Our ongoing work shows that this analogy can also be applied to electronic structure along the photoisomerization coordinates of some of the dyes studied here. It does seem to us now that there is a general physics underlying the excited state behavior in all of these systems, and an opportunity for the development and application of quite general model Hamiltonians for fluorogenic monomethine dyes.…”

Section: A General Discussionmentioning

confidence: 99%

A three-state effective Hamiltonian for symmetric cationic diarylmethanes

Olsen

McKenzie

2012

The Journal of Chemical Physics

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Comparison of density functionals for energy and structural differences between the high-[ 5 T 2g :(t 2g ) 4 (e g ) 2 ] and low-[ 1 A 1g :(t 2g ) 6 (e g ) 0 ] spin states of iron (II) We analyze the low-energy electronic structure of a series of symmetric cationic diarylmethanes, which are bridge-substituted derivatives of Michler's Hydrol Blue. We use a four-electron, threeorbital complete active space self-consistent field and multi-state multi-reference perturbation theory model to calculate a three-state diabatic effective Hamiltonian for each dye in the series. We exploit an isolobal analogy between the active spaces of the self-consistent field solutions for each dye to represent the electronic structure in a set of analogous diabatic states. The diabatic states can be identified with the bonding structures in classical resonance-theoretic models of cyanine dyes. We identify diabatic states with opposing charge and bond-order localization, analogous to the classical resonance structures, and a third state with charge on the bridge. While the left-and right-charged structures are similar for all dyes, the structure of the bridge-charged diabatic state, and the Hamiltonian matrix elements connected to it, change significantly across the series. The change is correlated with an inversion of the sign of the charge carrier on the bridge, which changes from an electron pair to a hole as the series is traversed.

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Section: A General Discussionmentioning

confidence: 99%

A three-state effective Hamiltonian for symmetric cationic diarylmethanes

Olsen

McKenzie

2012

The Journal of Chemical Physics

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“…106 This notion is broadly supported by spectra of gas-phase chromophore models with positively charged amine groups coordinating the imidazoloxy oxygen, which absorb at energies intermediate between the phenol and cationic forms. 107 The oxonol cation form discussed here is distinct from the iminium cationic form that has been discussed in the literature, 105 and whose absorption has been recorded in solution. 108 In the context of the model (2.2), we will refer to the "cyanine limit" as the limit where δ → 0.…”

Section: B Computational Quantum Chemistrymentioning

confidence: 99%

“…105 We invoke the imidazolol and cationic forms here because they allow sampling of complementary electronic structure at different proximity to the cyanine limit, 48,49 and are thus useful for testing the model in different regimes. There is a conserved hydrogen bond interaction between the imidazoloxy oxygen and a nearby arginine residue in all functional fluorescent proteins, and it may be appropriate to consider the imidazolol and oxonol cation forms as representing a strong limit of this interaction.…”

Section: B Computational Quantum Chemistrymentioning

confidence: 99%

A two-state model of twisted intramolecular charge-transfer in monomethine dyes

Olsen

McKenzie

2012

The Journal of Chemical Physics

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Articles you may be interested inModeling opto-electronic properties of a dye molecule in proximity of a semiconductor nanoparticle J. Chem. Phys. 139, 024105 (2013) A two-state model Hamiltonian is proposed, which can describe the coupling of twisting displacements to charge-transfer behavior in the ground and excited states of a general monomethine dye molecule. This coupling may be relevant to the molecular mechanism of environment-dependent fluorescence yield enhancement. The model is parameterized against quantum chemical calculations on different protonation states of the green fluorescent protein chromophore, which are chosen to sample different regimes of detuning from the cyanine (resonant) limit. The model provides a simple yet realistic description of the charge transfer character along two possible excited state twisting channels associated with the methine bridge. It describes qualitatively different behavior in three regions that can be classified by their relationship to the resonant (cyanine) limit. The regimes differ by the presence or absence of twist-dependent polarization reversal and the occurrence of conical intersections. We find that selective biasing of one twisting channel over another by an applied diabatic biasing potential can only be achieved in a finite range of parameters near the cyanine limit.

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“…The relative position of the donor carbonyl group with respect to the acceptor carbonyl group is unclear in the excited state. [52][53][54] Nonetheless, infrared spectroscopy suggests that the acceptor carbonyl stretching mode is preserved in the excited state, even though deprotonation of the phenolic oxygen has taken place. 35 If significant structural changes do not occur in the excited state, then the n!p* interaction could persist there.…”

Section: -27mentioning

confidence: 99%

A conserved interaction with the chromophore of fluorescent proteins

2011

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The chromophore of fluorescent proteins, including the green fluorescent protein (GFP), contains a highly conjugated imidazolidinone ring. In many fluorescent proteins, the carbonyl group of the imidazolidinone ring engages in a hydrogen bond with the side chain of an arginine residue. Prior studies have indicated that such an electrophilic carbonyl group in a protein often accepts electron density from a main-chain oxygen. A survey of high-resolution structures of fluorescent proteins indicates that electron lone pairs of a main-chain oxygen-Thr62 in GFP-donate electron density into an antibonding orbital of the imidazolidinone carbonyl group. This nfip* electron delocalization prevents structural distortion during chromophore excitation that could otherwise lead to fluorescence quenching. In addition, this interaction is present in on-pathway intermediates leading to the chromophore, and thus could direct its biogenesis. Accordingly, this nfip* interaction merits inclusion in computational and photophysical analyses of the chromophore, and in speculations about the molecular evolution of fluorescent proteins.

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Excited state reactions in fluorescent proteins

Cited by 292 publications

References 152 publications

A three-state effective Hamiltonian for symmetric cationic diarylmethanes

A three-state effective Hamiltonian for symmetric cationic diarylmethanes

A two-state model of twisted intramolecular charge-transfer in monomethine dyes

A conserved interaction with the chromophore of fluorescent proteins

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