Aerobic photolysis of methylcobalamin: unraveling the photoreaction mechanism

Ghosh, Arghya Pratim; Lodowski, Piotr; Kozłowski, Pawel M.

doi:10.1039/d1cp02013g

Cited by 6 publications

(3 citation statements)

References 81 publications

(127 reference statements)

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“…In terms of methodology choice for DFT calculations, previous studies from us, 5,24-28 but more importantly from Brunold and especially from Kozlowski on related systems have each indicated advantages for a functional or another. [29][30][31][32][33][34][35][36][37][38][39][40][41][42] We have, more in general, shown that even within the same class of compounds the performance of a functional can vary widely depending on the property sought, or on apparently simple changes in ligands (e.g., axial ligation in heme complexes). [43][44][45][46] The methodology employed here was selected for its ability to best mimic trends in UV-vis spectra as described in our previous study on hydroperoxocobalamin, thus also allowing consistency between the two sets of data.…”

Section: Methodsmentioning

confidence: 99%

“…In terms of methodology choice for DFT calculations, previous studies from us, 5,24–28 but more importantly from Brunold and especially from Kozlowski on related systems have each indicated advantages for a functional or another. 29–42 We have, more in general, shown that even within the same class of compounds the performance of a functional can vary widely depending on the property sought, or on apparently simple changes in ligands ( e.g. , axial ligation in heme complexes).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

A complex of cobalamin with an organic peroxide

Lehene,

Zăgrean-Tuza,

Hădade

et al. 2023

New J. Chem.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

A complex of cobalamin with an organic peroxide

Lehene,

Zăgrean-Tuza,

Hădade

et al. 2023

New J. Chem.

View full text Add to dashboard Cite

show abstract

“…[155]. Since then, this field has been updated by numerous publications and is still being researched [156][157][158][159][160][161][162]. Vitamin B 12 instability upon exposure to light is also recognized by the responsible authorities and manufacturers of vitamin B 12 preparations, which recommend that vitamin B 12 active ingredients (CNCbl, OHCbl, and MeCbl) and their preparations (injections and tablets) should be stored protected from light [140, 152,153].…”

Section: Ph Of the Solutionmentioning

confidence: 99%

Vitamin B12 in Foods, Food Supplements, and Medicines—A Review of Its Role and Properties with a Focus on Its Stability

et al. 2022

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Vitamin B12, also known as the anti-pernicious anemia factor, is an essential micronutrient totally dependent on dietary sources that is commonly integrated with food supplements. Four vitamin B12 forms—cyanocobalamin, hydroxocobalamin, 5′-deoxyadenosylcobalamin, and methylcobalamin—are currently used for supplementation and, here, we provide an overview of their biochemical role, bioavailability, and efficacy in different dosage forms. Since the effective quantity of vitamin B12 depends on the stability of the different forms, we further provide a review of their main reactivity and stability under exposure to various environmental factors (e.g., temperature, pH, light) and the presence of some typical interacting compounds (oxidants, reductants, and other water-soluble vitamins). Further, we explore how the manufacturing process and storage affect B12 stability in foods, food supplements, and medicines and provide a summary of the data published to date on the content-related quality of vitamin B12 products on the market. We also provide an overview of the approaches toward their stabilization, including minimization of the destabilizing factors, addition of proper stabilizers, or application of some (innovative) technological processes that could be implemented and contribute to the production of high-quality vitamin B12 products.

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Sequential C−H Methylation Catalyzed by the B₁₂‐Dependent SAM Enzyme TokK: Comprehensive Theoretical Study of Selectivities

Deng

Liao

2022

Chemistry A European J

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TokK is a B 12 -dependent radical SAM enzyme involved in the biosynthesis of the β-lactam antibiotic asparenomycin A. It can catalyze three methylations on different sp 3 -hybridized carbon positions to introduce an isopropyl side chain at the β-lactam ring of pantetheinylated carbapenem. Herein, we report a quantum chemical study of the reaction mechanism of TokK. A stepwise ''push-pull'' radical relay mechanism is proposed for each methylation: a 5'deoxyadenosine radical first abstracts a hydrogen atom from the substrate in the active site, then methylcobalamin direc-tionally donates a methyl group to the substrate. More importantly, calculations were able to uncover the origin of observed chemoselectivity and stereoselectivity for the first methylation and regioselectivity for the following two methylations. Further detailed distortion/interaction analysis can help to unravel the main factors controlling the selectivities. Our findings of sequential methylations by TokK could have profound implications for studying other B 12 -dependent radical SAM enzymes.

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Aerobic photolysis of methylcobalamin: unraveling the photoreaction mechanism

Abstract: The photo-reactivity of cobalamins (Cbls) is influenced by the nature of axial ligands and the cofactor’s environment. While the biologically active forms of Cbls with alkyl axial ligands, such as...

Cited by 6 publications

References 81 publications

A complex of cobalamin with an organic peroxide

A complex of cobalamin with an organic peroxide

Vitamin B12 in Foods, Food Supplements, and Medicines—A Review of Its Role and Properties with a Focus on Its Stability

Sequential C−H Methylation Catalyzed by the B₁₂‐Dependent SAM Enzyme TokK: Comprehensive Theoretical Study of Selectivities

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Aerobic photolysis of methylcobalamin: unraveling the photoreaction mechanism

Abstract: The photo-reactivity of cobalamins (Cbls) is influenced by the nature of axial ligands and the cofactor’s environment. While the biologically active forms of Cbls with alkyl axial ligands, such as...

Cited by 6 publications

References 81 publications

A complex of cobalamin with an organic peroxide

A complex of cobalamin with an organic peroxide

Vitamin B12 in Foods, Food Supplements, and Medicines—A Review of Its Role and Properties with a Focus on Its Stability

Sequential C−H Methylation Catalyzed by the B12‐Dependent SAM Enzyme TokK: Comprehensive Theoretical Study of Selectivities

Contact Info

Product

Resources

About

Sequential C−H Methylation Catalyzed by the B₁₂‐Dependent SAM Enzyme TokK: Comprehensive Theoretical Study of Selectivities