Ultrafast flavin/tryptophan radical pair kinetics in a magnetically sensitive artificial protein

Bialas, Chris; Barnard, David T.; Auman, Dirk B.; McBride, Rylee A.; Jarocha, Lauren E.; Hore, P. J.; Dutton, P. Leslie; Stanley, Robert J.; Moser, Christopher C.

doi:10.1039/c9cp01916b

Cited by 12 publications

(21 citation statements)

References 50 publications

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“…While flavins usually show ISC on a ns time scale, [10,26a] the deprotonated forms converts on the order of 100 ps, [26b] still being longer than the observed time range of 1 ps. In contrast, non‐specific ET is driven via an edge‐to‐edge tunneling for short distances within 25 ps or shorter, depending on the ion contact pair distance [26c] . Therefore, ultrafast non‐specific ET can be a competing pathway to direct ET with Trp.…”

Section: Resultsmentioning

confidence: 99%

“…The ET from Trp to the flavin moiety and the formation of the hydroquinone forms FlavinH − and FlavinH − 2 by non‐specific ET are competitive pathways. Since the latter formation involves a ion pair state, [26c] the reference system PR shows a dominant non‐specific ET whereas P0a has a weak non‐specific ET (cf. a weak band at 470 nm) and therefore a strengthened and directed ET.…”

Section: Discussionmentioning

confidence: 99%

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Directed Electron Transfer in Flavin Peptides with Oligoproline‐Type Helical Conformation as Models for Flavin‐Functional Proteins

et al. 2020

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To mimic the charge separation in functional proteins we studied flavin‐modified peptides as models. They were synthesized as oligoprolines that typically form a polyproline type‐II helix, because this secondary structure supports the electron transfer properties. We placed the flavin as photoexcitable chromophore and electron acceptor at the N‐terminus. Tryptophans were placed as electron donors to direct the electron transfer over 0–3 intervening prolines. Spectroscopic studies revealed competitive photophysical pathways. The reference peptide without tryptophan shows dominant non‐specific ET dynamics, leading to an ion pair formation, whereas peptides with tryptophans have weak non‐specific ET and intensified directed electron transfer. By different excitation wavelengths, we can conclude that the corresponding ion pair state of flavin within the peptide environment has to be energetically located between the S1 and S4 states, whereas the directed electron transfer to tryptophan occurs directly from the S1 state. These photochemical results have fundamental significance for proteins with flavin as redoxactive cofactor.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Directed Electron Transfer in Flavin Peptides with Oligoproline‐Type Helical Conformation as Models for Flavin‐Functional Proteins

et al. 2020

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“…The dramatic τ T reduction observed for Q50W can be attributed to electron transfer processes involving the tryptophan and 3 FMN moieties, including the formation of radical pairs. 16,17 Conversely, Q50E resembled the WT displaying a 3 FMN decay of 31 μs. The lifetime values obtained in this work for WT and Q103V are consistent with data previously reported.…”

Section: Q103mentioning

confidence: 94%

“…14,18 For the latter instead, the generation of FMN •-/Trp •+ radical pairs and back electron transfer processes may explain the low intensity of the 600-nm band, as well as the shorter 3 FMN* lifetime observed by transient absorption. 17 Notably, circular dichroism spectra of light-irradiated mSOG variants showed that formation of the FMN radical did not cause major changes in the protein structure ( Figure S8).…”

Section: Q103mentioning

confidence: 95%

Enhancing The Photocatalytic Conversion Of Pt(IV) Substrates By Flavoprotein Engineering

Gurruchaga-Pereda¹,

Martínez‐Martínez²,

Formoso³

et al. 2021

Preprint

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Our recent work demonstrates that certain flavoproteins can catalyze the redox activation of Pt(IV) prodrug complexes under light irradiation. Herein, we used site directed mutagenesis on the mini Singlet Oxygen Generator (mSOG) to modulate the photocatalytic activity of this flavoprotein towards two model Pt(IV) substrates. Among the prepared mutants, Q103V mSOG displayed enhanced catalytic efficiency as a result of its longer triplet excited state lifetime. This study shows, for the first time, that protein engineering can improve the catalytic capacity of a protein towards metal-containing substrate.

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“…From this perspective, nonstatic magnetic field sensitivity would not be an evolutionary capacity driven by seismic events, but a collateral/derived capacity consisting of a lowered response threshold. To explain the biological effects of weak magnetic fields, some molecular transduction mechanisms have been proposed (Binhi and Prato 2018;Bialas et al, 2019). While for animal navigation/orientation, the main hypothesis is a specialized magnetic sense associated with pairs of radicals located in the retina of the eye, nonspecific effects could occur due to the interaction of magnetic fields with the magnetic moments of rotating molecules dispersed in the organism.…”

Section: Reports On Earthquake Lightsmentioning

confidence: 99%

A Critical Review of Ground Based Observations of Earthquake Precursors

2021

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We aim at giving a short review of the seismo-associated phenomena detected on ground that in recent years have been investigated as possible earthquake precursors. The paper comes together with a companion article–published on this same volume by Picozza et al., 2021–devoted to summarize the space-based observation of earthquake–precursors by satellites missions. In the present work, we give an overview of the observations carried out on ground in order to identify earthquake precursors by distinguishing them from the large background constituted by both natural non-seismic and artificial sources. We start discussing the measurements of mechanical parameters and variations of geochemical fluids detected before earthquakes; then we review thermal and atmospheric oscillations; finally, observations of electromagnetic and ionospheric parameters possibly related to the occurrence of impeding earthquakes are discussed. In order to introduce a so large field of research, we focus only on some main case studies and statistical analyses together with the main hypotheses and models proposed in literature in order to explain the observed phenomenology.

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Ultrafast flavin/tryptophan radical pair kinetics in a magnetically sensitive artificial protein

Abstract: Flavin/tryptophan radical pairs in artificial proteins demonstrate that singlet- and triplet-born pairs can be exploited as biological magnetic sensors.

Cited by 12 publications

References 50 publications

Directed Electron Transfer in Flavin Peptides with Oligoproline‐Type Helical Conformation as Models for Flavin‐Functional Proteins

Directed Electron Transfer in Flavin Peptides with Oligoproline‐Type Helical Conformation as Models for Flavin‐Functional Proteins

Enhancing The Photocatalytic Conversion Of Pt(IV) Substrates By Flavoprotein Engineering

A Critical Review of Ground Based Observations of Earthquake Precursors

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