Photolysis of methylcobalamin in aqueous solution: A kinetic study

Vaid, Faiyaz H.M.; Zahid, Saima; Faiyaz, Ambreen; Qadeer, Kiran; Gul, Wajiha; Anwar, Zubair; Ahmad, Iqbal

doi:10.1016/j.jphotochem.2018.05.011

Cited by 20 publications

(16 citation statements)

References 53 publications

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“…Considering that the two active forms (i.e. MB12 and AB12) have been described as photolabile (Juzeniene and Nizauskaite, 2013; Juzeniene et al ., 2015; Vaid et al ., 2018), it could be expected that their contribution to the total dissolved pool in surface waters should be small. The only two studies measuring the four B12 congeners (MB12, AB12, HB12 and CB12) reported disparate average contribution of HB12 to the total dissolved B12 pool, representing ca.…”

Section: Discussionmentioning

confidence: 99%

“…MB12 is the active form of cobalamin that is used by organisms for the synthesis of methionine through the cobalamin‐dependent methionine synthase (MetH) (Matthews et al ., 2003) and AB12 is the coenzyme for methylmalonyl‐CoA mutase, which is an essential enzyme in the metabolism of odd‐chain fatty acids (Marsh, 1999). MB12 and AB12 are considered as extremely photolabile and quickly degrade to HB12 when exposed to light (Juzeniene and Nizauskaite, 2013; Juzeniene et al ., 2015; Vaid et al ., 2018). The lower axial ligand of this molecule can also present diversity, with 5,6 dimethylbenzimidazole or adenine building, respectively, cobalamin or pseudocobalamin (Stupperich and Krautler, 1988; Watanabe et al ., 1999; Helliwell et al ., 2016; Heal et al ., 2017).…”

Section: Introductionmentioning

confidence: 99%

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Cobalamin and microbial plankton dynamics along a coastal to offshore transect in the Eastern North Atlantic Ocean

Joglar

Álvarez‐Salgado

Gago-Martı́nez

et al. 2021

Environmental Microbiology

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Cobalamin (B12) is an essential cofactor that is exclusively synthesized by some prokaryotes while many prokaryotes and eukaryotes require an external supply of B12. The spatial and temporal availability of B12 is poorly understood in marine ecosystems. Field measurements of B12 along with a large set of ancillary biotic and abiotic factors were obtained during three oceanographic cruises in the NW Iberian Peninsula, covering different spatial and temporal scales. B12 concentrations were remarkably low (<1.5 pM) in all samples, being significantly higher at the subsurface Eastern North Atlantic Central Water than at shallower depths, suggesting that B12 supply in this water mass is greater than demand. Multiple regression models excluded B12 concentration as predictive variable for phytoplankton biomass or production, regardless of the presence of B12-requiring algae. Prokaryote production was the best predictor for primary production, and eukaryote community composition was better correlated with prokaryote community composition than with nutritional resources, suggesting that biotic interactions play a significant role in regulating microbial communities. Interestingly, co-occurrence network analyses based on 16S and 18S rRNA sequences allowed the identification of significant associations between potential B12 producers and consumers (e.g. Thaumarchaeota and Dynophyceae, or Amylibacter and Ostreococcus respectively), which can now be investigated using model systems in the laboratory.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cobalamin and microbial plankton dynamics along a coastal to offshore transect in the Eastern North Atlantic Ocean

Joglar

Álvarez‐Salgado

Gago-Martı́nez

et al. 2021

Environmental Microbiology

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“…The quantum yields of LG release from cobalamin derivatives are often irradiation-wavelength dependent. ,, For example, the Φ r for • CH 3 liberation from methylcobalamin in aerated aqueous solutions varies from 0.35 at λ irr = 490 nm to 0.24 at Φ r = 550 nm. , Similarly, 5′-deoxyadenosylcobalamin undergoes Co–C bond cleavage with Φ r = 0.20 under anaerobic conditions, although a near-unity quantum yield for bond homolysis in aqueous solution has also been reported for this compound . The Co II side-product can be trapped by oxygen. ,, The photolysis mechanism and release quantum yields depend not only on the type of LG but also on experimental parameters including the solvent, the pH, the presence of specific enzymes, ,,,− and the nature of the lower axial base. , Cobalamin release mechanisms are discussed in more detail in a recent review by Jones …”

Section: Photorelease From Coordination Compoundsmentioning

confidence: 99%

Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials

et al. 2020

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Photoactivatable (alternatively, photoremovable, photoreleasable, or photocleavable) protecting groups (PPGs), also known as caged or photocaged compounds, are used to enable non-invasive spatiotemporal photochemical control over the release of species of interest. Recent years have seen the development of PPGs activatable by biologically and chemically benign visible and near-infrared (NIR) light. These long-wavelength-absorbing moieties expand the applicability of this powerful method and its accessibility to non-specialist users. This review comprehensively covers organic and transition metal-containing photoactivatable compounds (complexes) that absorb in the visible- and NIR-range to release various leaving groups and gasotransmitters (carbon monoxide, nitric oxide, and hydrogen sulfide). The text also covers visible- and NIR-light-induced photosensitized release using molecular sensitizers, quantum dots, and upconversion and second-harmonic nanoparticles, as well as release via photodynamic (photooxygenation by singlet oxygen) and photothermal effects. Release from photoactivatable polymers, micelles, vesicles, and photoswitches, along with the related emerging field of photopharmacology, is discussed at the end of the review.

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“…UV-photolysis is a popular way for producing free radicals via cleavage of sigma-bond (Moreira et al, 2017;Vaid et al, 2018). Generated radicals exist normally as precursors which produce more free radicals.…”

Section: Effect Of Dye Concentration On Its % Decolorization In Photomentioning

confidence: 99%

Oxidative decolorization of a malachite green oxalate dye through the Photochemical Advanced Oxidation Processes

Ghime¹,

Goru²,

Ojha³

et al. 2019

Global NEST: The International Journal

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<p>This report was aimed at an investigation of efficiency for Photochemical Advanced Oxidation Processes (UV photolysis, UV/H2O2, UV/TiO2, UV/H2O2/TiO2 and UV/H2O2/Fe2+ processes) to decolorize Malachite Green Oxalate (MGO) dye. Experimental runs were performed using laboratory scale photochemical reactor. About 98% decolorization was obtained with initial 100 ppm MGO dye in Photo-Fenton process under optimal conditions (60 ppm Fe2+ concentration, 12 mM of oxidant concentration, at pH 3.0 for 60 min). 97% decolorization was obtained using UV/H2O2/TiO2 process having [TiO2]o of 0.6 gm/L for similar reaction conditions. The percentage decolorization of MGO was in range of 94-95% for both UV/TiO2 and UV/H2O2 processes. Concentration of ferrous salt (60 ppm) was considered as an optimal value to carry out the UV/H2O2/Fe2+ process for MGO decolorization. Influence of oxidant (H2O2) and Fe2+ ions for oxidation of MGO was studied in Photo-Fenton process. Sulphate radical based AOPs was proved to be more effective in treating MGO dye with irradiation. Results indicate that decolorization efficiency by Photochemical AOPs for MGO dye in photochemical reactor were more efficient. Pseudo-first-order model of kinetics was noticed to be the best model fit to explain the decolorization of MGO dye solution.</p>

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Photolysis of methylcobalamin in aqueous solution: A kinetic study

Cited by 20 publications

References 53 publications

Cobalamin and microbial plankton dynamics along a coastal to offshore transect in the Eastern North Atlantic Ocean

Cobalamin and microbial plankton dynamics along a coastal to offshore transect in the Eastern North Atlantic Ocean

Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials

Oxidative decolorization of a malachite green oxalate dye through the Photochemical Advanced Oxidation Processes

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