Evidence That the (6−4) Photolyase Mechanism Can Proceed through an Oxetane Intermediate

Asgatay, Saâdia; Petermann, Christian; Harakat, Dominique; Guillaume, Dominique; Taylor, John‐Stephen; Clivio, Pascale

doi:10.1021/ja805214s

Cited by 23 publications

(26 citation statements)

References 27 publications

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“…(Figure ). Experimental and theoretical studies have been performed intensively over the past years, to trace all steps of the repair. While the functional mechanism of CPD photolyases has been identified, the details of the repair mechanism operating in (6‐4) photolyases is still a matter of ongoing debate.…”

Section: Figurementioning

confidence: 99%

“…Until today, various mechanisms of 6‐4PP repair initiated by the catalytic electron have been proposed, out of which the following five are considered to be the most promising candidates: I) The oxetane mechanism, which represents one of the earliest proposed mechanism in the literature. Here, 6‐4PP is assumed to be converted to an oxetane ring, which requires the attack of the O4′ oxygen at the C4′ carbon involving intermediate I (Figure ).…”

Section: Figurementioning

confidence: 99%

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Characterization of the Intermediate in and Identification of the Repair Mechanism of (6‐4) Photolesions by Photolyases

2016

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Quantum mechanics/molecular mechanics calculations are employed to assign previously recorded experimental spectroscopic signatures of the intermediates occurring during the photo-induced repair of (6-4) photolesions by photolyases to specific molecular structures. Based on this close comparison of experiment and theory it is demonstrated that the acting repair mechanism involves proton transfer from the protonated His365 to the N3′ nitrogen of the lesion, which proceeds simultaneously with intramolecular OH transfer along an oxetane-like transition state.

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Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Characterization of the Intermediate in and Identification of the Repair Mechanism of (6‐4) Photolesions by Photolyases

2016

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“…Support for the oxetane‐intermediate mechanism came from a study with model compounds (a 64PP containing a 3′‐thymine‐4‐methylthymine molecule), which was irradiated and repaired without the participation of an enzyme [70]. By careful assignment of the intermediate structures, the authors concluded that an oxetane intermediate in the 64PP repair reaction seems most likely.…”

Section: Epr/endor Investigations Of (6‐4) Photolyasementioning

confidence: 99%

New roles of flavoproteins in molecular cell biology: Blue‐light active flavoproteins studied by electron paramagnetic resonance

2009

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Exploring enzymatic mechanisms at a molecular level is one of the major challenges in modern biophysics. Based on enzyme structure data, as obtained by X‐ray crystallography or NMR spectroscopy, one can suggest how substrates and products bind for catalysis. However, from the 3D structure alone it is very rarely possible to identify how intermediates are formed and how they are interconverted. Molecular spectroscopy can provide such information and thus supplement our knowledge on the specific enzymatic reaction under consideration. In the case of enzymatic processes in which paramagnetic molecules play a role, EPR and related methods such as electron‐nuclear double resonance (ENDOR) are powerful techniques to unravel important details, e.g. the electronic structure or the protonation state of the intermediate(s) carrying (the) unpaired electron spin(s). Here, we review recent EPR/ENDOR studies of blue‐light active flavoproteins with emphasis on photolyases that catalyze the enzymatic repair of UV damaged DNA, and on cryptochrome blue‐light photoreceptors that act in several species as central components of the circadian clock.

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“…22,23,24,25,26,27 The idea that (6-4) photoproducts are converted to oxetanes (or azetidines) upon binding to the enzyme in the dark has been questioned based on the crystal structure of a model (6-4) photoproduct in the binding pocket. 28,29 In general, experimental and theoretical studies assume that (6-4) photoproducts are repaired upon absorption of a single photon by the enzyme.…”

Section: Electron Transfer-mediated Hetero Cycloreversionsmentioning

confidence: 99%

Hetero-cycloreversions Mediated by Photoinduced Electron Transfer

2014

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The Diels-Alder cycloaddition was discovered more than eight decades ago; however, it still remains one of the most versatile tools in synthetic organic chemistry, and its mechanism continues to attract considerable interest, both from the experimental and theoretical points of view. Specifically, hetero-Diels This account deals with electron transfer-mediated hetero cycloaddition and cycloreversion reactions. The attention has been focused on the ionization of oxadienes, azadienes and thiadienes, to give six-membered heterocycles, as well as on the oxidative and reductive electron transfer splitting of oxetanes, azetidines and thietanes.

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Evidence That the (6−4) Photolyase Mechanism Can Proceed through an Oxetane Intermediate

Cited by 23 publications

References 27 publications

Characterization of the Intermediate in and Identification of the Repair Mechanism of (6‐4) Photolesions by Photolyases

Characterization of the Intermediate in and Identification of the Repair Mechanism of (6‐4) Photolesions by Photolyases

New roles of flavoproteins in molecular cell biology: Blue‐light active flavoproteins studied by electron paramagnetic resonance

Hetero-cycloreversions Mediated by Photoinduced Electron Transfer

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