Mechanism of Co–C photodissociation in adenosylcobalamin

Garabato, Brady D.; Lodowski, Piotr; Jaworska, Maria; Kozłowski, Pawel M.

doi:10.1039/c6cp02136k

Cited by 27 publications

(39 citation statements)

References 55 publications

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“…Exclusive use of these metabolites likely reflects their ready availability. Photolysis of adenosylcobalamin causes loss of its adenosyl group (Garabato et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Underlying mechanisms for syntrophic metabolism of essential enzyme cofactors in microbial communities

et al. 2017

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Many microorganisms are unable to synthesize essential B vitamin-related enzyme cofactors de novo. The underlying mechanisms by which such microbes survive in multi-species communities are largely unknown. We previously reported the near-complete genome sequence of two ~18-member unicyanobacterial microbial consortia that maintain stable membership on defined medium lacking vitamins. Here we have used genome analysis and growth studies on isolates derived from the consortia to reconstruct pathways for biogenesis of eight essential cofactors and predict cofactor usage and precursor exchange in these communities. Our analyses revealed that all but the two Halomonas and cyanobacterial community members were auxotrophic for at least one cofactor. We also observed a mosaic distribution of salvage routes for a variety of cofactor precursors, including those produced by photolysis. Potentially bidirectional transporters were observed to be preferentially in prototrophs, suggesting a mechanism for controlled precursor release. Furthermore, we found that Halomonas sp. do not require cobalamin nor control its synthesis, supporting the hypothesis that they overproduce and export vitamins. Collectively, these observations suggest that the consortia rely on syntrophic metabolism of cofactors as a survival strategy for optimization of metabolic exchange within a shared pool of micronutrients.

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“…Exclusive use of these metabolites likely reflects their ready availability. Photolysis of adenosylcobalamin causes loss of its adenosyl group (Garabato et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Underlying mechanisms for syntrophic metabolism of essential enzyme cofactors in microbial communities

et al. 2017

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“…Optical excitation results in a prompt electronic change in the π orbitals of the corrin ring and may include some involvement of Co d orbitals. 38,42 The earliest change observed in the X-ray absorption spectrum is the decrease in absorption of the sharp 1s → 3d transition at 7.711 keV. The bleach of this signal appears on a time scale that is consistent with the temporal width and overlap of the X-ray and optical pulses at the sample.…”

Section: ■ Introductionmentioning

confidence: 81%

Ultrafast XANES Monitors Femtosecond Sequential Structural Evolution in Photoexcited Coenzyme B₁₂

et al. 2019

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Polarized X-ray absorption near-edge structure (XANES) at the Co K-edge and broadband UV–vis transient absorption are used to monitor the sequential evolution of the excited-state structure of coenzyme B12 (adenosylcobalamin) over the first picosecond following excitation. The initial state is characterized by sub-100 fs sequential changes around the central cobalt. These are polarized first in the y-direction orthogonal to the transition dipole and 50 fs later in the x-direction along the transition dipole. Expansion of the axial bonds follows on a ca. 200 fs time scale as the molecule moves out of the Franck–Condon active region of the potential energy surface. On the same 200 fs time scale there are electronic changes that result in the loss of stimulated emission and the appearance of a strong absorption at 340 nm. These measurements provide a cobalt-centered movie of the excited molecule as it evolves to the local excited-state minimum.

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“…As proposed by Kozlowski, photodissociation proceeds presumably from the first electronically excited state (S1) through the generation of a singlet radical pair. [34][35][36]…”

Section: Figure 1 Mechanistic Experimentsmentioning

confidence: 99%

Radical Ring-Opening of Oxetanes Enabled by Co-Catalysis

Potrząsaj¹,

Ociepa²,

Chaładaj³

et al. 2021

Preprint

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Oxetanes are valuable building blocks due to their well-explored propensity to undergo ring-opening reactions with diverse nucleophiles. However, their application as precursors of radical species remains unexplored. Herein, we present a cobalt catalysis-based strategy to access various modes of radical reactivity via oxetane ring opening. The developed method involves formation of an alkylated Co-complex intermediate from vitamin B12 and oxetane. Homolytic cleavage of the Co-C bond generates nucleophilic radicals that engage in reactions with SOMOphiles and low-valent transition metals. The scope of the developed reactions is broad with various functional groups being well tolerated. Importantly, the regioselectivity of these processes complements known methodologies.

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Mechanism of Co–C photodissociation in adenosylcobalamin

Cited by 27 publications

References 55 publications

Underlying mechanisms for syntrophic metabolism of essential enzyme cofactors in microbial communities

Underlying mechanisms for syntrophic metabolism of essential enzyme cofactors in microbial communities

Ultrafast XANES Monitors Femtosecond Sequential Structural Evolution in Photoexcited Coenzyme B₁₂

Radical Ring-Opening of Oxetanes Enabled by Co-Catalysis

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Mechanism of Co–C photodissociation in adenosylcobalamin

Cited by 27 publications

References 55 publications

Underlying mechanisms for syntrophic metabolism of essential enzyme cofactors in microbial communities

Underlying mechanisms for syntrophic metabolism of essential enzyme cofactors in microbial communities

Ultrafast XANES Monitors Femtosecond Sequential Structural Evolution in Photoexcited Coenzyme B12

Radical Ring-Opening of Oxetanes Enabled by Co-Catalysis

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Ultrafast XANES Monitors Femtosecond Sequential Structural Evolution in Photoexcited Coenzyme B₁₂