Vitamin B12 Molecules Research Articles

Electrocatalytic urea synthesis from CO2 and nitrate co-reduction on natural vitamin B12 coupled carbon nanotubes

The synthesis of urea from CO2 and nitrate co-electrolysis is highly attractive for the sustainable production of nitrogen-containing fertilizers such as urea. However, this process requires electrocatalysts that are not only highly active but also selective. In this study, we present a remarkable approach wherein Vitamin B12 is immobilized on the surface of carbon nanotubes to catalyze the co-electroreduction to urea under ambient conditions. This unique hybrid system, incorporating a naturally abundant molecular catalyst, exhibits exceptional selectivity and maintains a constant current density in CO2-saturated 0.1 M KNO3. Remarkably, we achieved a Faradaic efficiency (FE) of 26.04% at −0.5 V versus the reversible hydrogen electrode (RHE), resulting in a production yield of 164.04 μg h−1 mg−1 and an impressive turnover number (TON) reaching up to 830.53 while demonstrating excellent stability and durability over a period of 50 hours. Our experimental findings are further supported by density functional theory (DFT) studies that shed light on the influence exerted by the covalently attached and redox-active benzimidazole unit within Vitamin B12 molecule itself when immobilized onto conductive surfaces like carbon nanotubes. This work represents an unprecedented example where naturally abundant vitamin has been successfully immobilized on a conductive surface for achieving highly efficient electroproduction of urea.

Determination of vitamin B12 in dry mixtures for baby food by the method of high performance liquid chromatography with chromatomass-spectrometric detection

Relevance. Vitamin B12 (cobalamin) belongs to the group of water-soluble vitamins. This vitamin belongs to the class of tetrapyrroles, biologically active substances consisting of pyrrole rings associated with metal ions. So, in the vitamin B12 molecule, the core is the cobalt ion. A feature of this vitamin is that its synthesis in nature is carried out only by bacteria, and therefore, it is present only in products of animal origin. And one of the sources of its receipt is milk and dairy products, including those enriched with B vitamins. Low concentrations of vitamin B12, even in vitamin-enriched dairy products, at the level of tenths and hundredths of a milligram, make the assessment of its quantitative content a difficult analytical task. The use of reversed-phase liquid chromatography for this purpose, followed by detection by means of a spectrophotometric or diode-array detector, is associated with a time-consuming sample preparation technique. Including repeated concentration of the sample to achieve the required concentrations of the desired substance. In this connection, the development of an analytical method that allows to remove the disadvantages described above, is an urgent task.Methods. This article proposes a method for assessing the content of vitamin B12 by high performance liquid chromatography using a mass-spectrometric detector (HPLCMS). The method developed in this study can be used for laboratory analysis of vitamin B12 in dry formulas for baby food, which will provide the possibility of faster and more efficient results for the control and monitoring of baby food enriched with vitamin complexes of water-soluble vitamins of group B.Results. A method of sample preparation is presented, in which the recovery coefficient of the analyte in the studied samples was 99.12–99.31%. When evaluating the calibration curve, the correlation coefficient was r2 = 99.999. The calculated limit of detection is 0.02 g/kg.

Analisis Kadar Nrf2 plasma Pada Tikus dengan Defisisensi Vitamin B12

Background. Vitamin B12 deficiency is a significant problem, particularly in developing countries. The increasing complexity of the Vitamin B12 molecule, the deficiency condition, causes a complex cell level disorder. The clinical manifestation of vitamin B12 deficiency is anemia, but it is believed that due to the complexity of vitamin B12, there are still other molecular disorders. This study aims to establish the pathway of damage caused by vitamin B12 deficiency in the Nrf2 molecule.
 Methods. An animal experiment involving 12 male Sprague Dawley rats were randomly divided into control and 16-week treatment. There are two research groups, namely the control group and the treatment group. The control group was given a standard diet, while the treatment group was assigned a vitamin B12 deficiency diet. At the end of treatment, The levels of vitamin B12 in the liver tissue and plasma NRF2 were measured.
 Statistical Analysis. Nrf2 and vitamin B12 levels were statistically analyzed using the Student's T-test, and the correlation between vitamin B12 and Hb was analyzed using the Spearmen test. Data that cannot use by Independent T-test were tested using the Mann Whitney test.
 Results/Conclusion. There was no significant difference between the control and treatment groups on plasma Nrf2 levels (4.02 ± 0.59 pg/ml vs 3.34 ± 0.55 pg/ml; p = 0.07) and tissue vitamin B12 (0.0035 ± 0.0016 µg/ml vs 0.0030 ± 0.0006 µg/ml ; p = 0.8).
 Keywords: Nrf2 Plasma, Defisiensi, Vitamin B12

Molecular interactions between Vitamin B12 and membrane models: A biophysical study for new insights into the bioavailability of Vitamin

Vitamin B12 (VB12) deficiency is one of the most common malnutrition problems worldwide and is related to its poor bioavailability. The lipid composition of cell membranes and molecule-cell membrane lipid interactions are major factors affecting the bioavailability of nutrients. So, the study of these interactions may allow predicting the behavior of VB12 at cellular membranes and the effects on its activity. Thus, lipid vesicles with lipid composition similar to the majority of eukaryotic cell membranes were used as biomembrane models, and their interactions with VB12 molecules were evaluated. For that, different parameters were assessed such as the lipophilicity of VB12, its preferential location in the membrane and its effect on the physical properties of the bilayer. VB12 showed high affinity for the biological membranes, not inducing any biophysical changes in their properties. The interactions of VB12 with the membrane was affected by the complexity of the bilayer, since its increase in order and rigidity hinders the diffusion of molecules. Thus, the low bioavailability of VB12 is not related with its interactions with the biological membranes.

A Rapid Quantitative Chemiluminescence Immunoassay for Vitamin B12 in Human Serum.

Vitamin B12 is very important for the human body. Early diagnosis of vitamin B12 deficiency is essential because it is associated with many problems such as fatigue, lethargy, depression, poor memory, breathlessness, headaches, pale skin, mania, psychosis, etc. Most of the vitamin B12 molecules in serum bind to specific proteins as a complex; so, although researchers have developed some sensitive methods to quantify vitamin B12, few can be used for human serum detection of vitamin B12 because of disturbed releasing process. In this study, we are aiming to develop a rapid and accurate chemiluminescence immunoassay (CLIA) for human serum testing. In this study, we studied and optimized labelling of biotin molecules to vitamin B12 binding protein which had been extracted from hog gastric mucus, labelling of vitamin B12 molecules to horse radish peroxidase (HRP), releasing of vitamin B12 from its bound state in serum, concentrations of reagents, and incubation times. The developed method shows good performance and thermo-stability. The limit of detection (LOD) is 41 pg/mL, the recovery rate is 90.7% - 107.4%. The intra-assay CV is 4.4% - 8.0% and the inter-assay CV is 4.5% - 12.1%. Cross reactivity (CR) values are 49.4% for hydroxocobalamin and lower than 0.1% for vitamin B1, B2, B3, B9, and C. The method comparison results show that the correlation coefficient (R2) is 0.91, with a slight negative bias of -4.1% [95% limits of agreement (± 1.96 SD); -39.6% to 31.6%]. The developed method shows high sensitivity and specificity and good correlation using a Beckman Coulter instrument while the whole test needs only 40 minutes. It can fully satisfy the very busy clinical labs.

Deep-ultraviolet laser ablation electrospray ionization mass spectrometry.

A 193-nm wavelength deep ultraviolet laser was used for ambient laser ablation electrospray ionization mass spectrometry of biological samples. A pulsed ArF excimer laser was used to ablate solid samples, and the resulting plume of the desorbed material merged with charged electrospray droplets to form ions that were detected with a quadrupole time-of-flight mass spectrometer. Solutions containing peptide and protein standards up to 66-kDa molecular weight were deposited on a metal target, dried, and analyzed. No fragmentation was observed from peptides and proteins as well as from the more easily fragmented vitamin B12 molecule. The mass spectra contained peaks from multiply charged ions that were identical to conventional electrospray. Deep UV laser ablation of tissue allowed detection of lipids from untreated tissue. The mechanism of ionization is postulated to involve absorption of laser energy by a fraction of the analyte molecules that act as a sacrificial matrix or by residual water in the sample.

Trace determination of vitamin B12 in food samples by using Fe3O4 magnetic particles including multi-walled carbon nanotubes and nanodiamonds

A sensitive and simple determination method for trace vitamin B12 molecules was developed based on magnetic solid phase extraction (MSPE) by using newly synthesized magnetic nanoparticles.

Single-molecule visualization of conformational changes and substrate transport in the vitamin B12 ABC importer BtuCD-F

ATP-binding cassette (ABC) transporters form the largest class of active membrane transport proteins. Binding and hydrolysis of ATP by their highly conserved nucleotide-binding domains drive conformational changes of the complex that mediate transport of substrate across the membrane. The vitamin B12 importer BtuCD-F in Escherichia coli is an extensively studied model system. The periplasmic soluble binding protein BtuF binds the ligand; the transmembrane and ATPase domains BtuCD mediate translocation. Here we report the direct observation at the single-molecule level of ATP, vitamin B12 and BtuF-induced events in the transporter complex embedded in liposomes. Single-molecule fluorescence imaging techniques reveal that membrane-embedded BtuCD forms a stable complex with BtuF, regardless of the presence of ATP and vitamin B12. We observe that a vitamin B12 molecule remains bound to the complex for tens of seconds, during which several ATP hydrolysis cycles can take place, before it is being transported across the membrane.

Properties of adsorption of vitamin B12 on nanoclay as a versatile carrier.

In this study properties of adsorption of vitamin B12 onto nanoclay were investigated. Results of kinetics of adsorption were used to investigate the structural formation and nature of interaction of vitamin B12 onto montmorillonite as a carrier. The results showed that at the early stages of adsorption with migration of interlayer cations of montmorillonite (Ca2+and Na+) to the edges a cationic bridge was formed and the vitamin biomolecules were adsorbed at the edges of montmorillonite. By increasing the adsorption duration, vitamin B12 molecules gradually diffused in between montmorillonite layers. Such diffusion was facilitated when enough interaction existed between montmorillonite surface charges and vitamin biomolecules. The results of this study provided information about controlling the adsorption properties of biomolecules to the montmorillonite for preparation of nano-engineered nano/biomaterials for food and pharmaceutical applications.

Sensitization of ZnO nanoparticle by vitamin B12: Investigation of microstructure, FTIR and optical properties

Vitamin B12 (VB12) as a biomolecule was successfully applied to modify the as-synthesized ZnO nanoparticles (NPs). VB12–ZnO conjugate was fabricated by a solution based method, the phase component of which was independent of the modification process, as shown by X-ray diffraction (XRD) analysis. The amount of loaded VB12 on ZnO NPs was measured by thermal gravimetry (TGA) to be∼25wt.%. Fourier transform infrared (FTIR) spectroscopy was used to probe the interaction of ZnO NPs with VB12. Although the sensitization process did not cause the appearance of any intense new peak in the FTIR results, the traces of a new band at 756cm−1 and also the intensification of the peak at 3411cm−1 (in comparison to ZnO spectrum) confirmed the formation of some new bands between NPs and VB12 molecules. The UV–vis spectroscopy revealed that VB12–ZnO conjugate absorbed light irradiation at around 272, 380 and 454nm. The third one is situated in the visible light region, originating from the conjugation between ZnO NPs and the functional ring of VB12. The photoluminescence (PL) behavior was affected by the sensitization process, shifting the PL peak of ZnO NPs toward a higher wavelength and increasing its intensity.

Mesoporous-silica-coated upconversion nanoparticles loaded with vitamin B12 for near-infrared-light mediated photodynamic therapy

Near-infrared (NIR)-to-visible upconversion nanotechnology has potential to be used for photodynamic therapy (PDT) because the use of NIR-irradiation provides deep tissue penetration and avoids photodamge to nomal cells, thus overcoming a major hurdle in the treatment of deep-seated tumors. In this study, a novel nano-platform of mesoporous-silica-coated NaYF4:Yb/Er upconverting nanoparticles with a large surface area of 770m2/g and an average pore size of 2nm, was fabricated and used for NIR-mediated PDT. Vitamin B12 (VB12), a nontoxic, easy-to-obtain and biocompatible photosensitizer, was incorporated into the mesoporous silica and used as PDT drug. There is a good overlap (545nm) between the fluorescence emission of NaYF4:Yb/Er nanoparticles and the UV–visible absorption of VB12. Under NIR-irradiation, the visible fluorescent emission from the upconverting nanoparticles will be absorbed by the VB12 coated on their surfaces. Then, the VB12 molecules under excited-state interact with surrounding ground-state molecular oxygen, generating reactive oxygen species, leading to oxidative damage of cancer cells.

Pyrolysis of polyaniline–poly(styrene sulfonate) hydrogels to prepare activated carbons for the adsorption of vitamin B12

In this study, polyaniline–poly(styrene sulfonate) (PAn–PSS) hydrogels were pyrolyzed to obtain activated carbons for the adsorption of vitamin B12 molecules for the first time. The structural properties of the as-prepared activated carbons were characterized with scanning electron microscope (SEM), nitrogen absorption–desorption, and Fourier transform infrared spectroscopy (FTIR). The resulting activated carbon samples maintained the previous network structure of the hydrogels. The optimum carbonization temperature was determined. The activated carbons which were prepared under the optimum condition possessed high mesoporous ratio of above 70%. In addition, these activated carbon samples were nitrogen-enriched due to the PAn–PSS precursor. The adsorption tests indicated that these activated carbons had preferable adsorption ability for vitamin B12 and were favorable to be used in the separation and purification of vitamin B12. Adsorption data of vitamin B12 on PAn–PSS based activated carbons were well modeled by Langmuir equation. The adsorption kinetic data were following the pseudo second order model.

Analyses of cobalt-ligand and potassium-ligand bond lengths in metalloproteins: trends and patterns.

Cobalt and potassium are biologically important metal elements that are present in a large array of proteins. Cobalt is mostly found in vivo associated with a corrin ring, which represents the core of the vitamin B12 molecule. Potassium is the most abundant metal in the cytosol, and it plays a crucial role in maintaining membrane potential as well as correct protein function. Here, we report a thorough analysis of the geometric properties of cobalt and potassium coordination spheres that was performed with high resolution on a representative set of structures from the Protein Data Bank and complemented by quantum mechanical calculations realized at the DFT level of theory (B3LYP/ SDD) on mononuclear model systems. The results allowed us to draw interesting conclusions on the structural characteristics of both Co and K centers, and to evaluate the importance of effects such as their association energies and intrinsic thermodynamic stabilities. Overall, the results obtained provide useful data for enhancing the atomic models normally applied in theoretical and computational studies of Co or K proteins performed at the quantum mechanical level, and for developing molecular mechanical parameters for treating Co or K coordination spheres in molecular mechanics or molecular dynamics studies.

Elucidating the origin of the ExbBD components of the TonB system through Bayesian inference and maximum-likelihood phylogenies

Uptake of ferric siderophores, vitamin B12, and other molecules in gram-negative bacteria is mediated by a multi-protein complex known as the TonB system. The ExbB and ExbD protein components of the TonB system play key energizing roles and are homologous with the flagellar motor proteins MotA and MotB. Here, the phylogenetic relationships of ExbBD and MotAB were investigated using Bayesian inference and the maximum-likelihood method. Phylogenetic trees of these proteins suggest that they are separated into distinct monophyletic groups and have originated from a common ancestral system. Several horizontal gene transfer events for ExbB–ExbD are also inferred, and a model for the evolution of the TonB system is proposed.

On designing particulate carriers for encapsulation and controlled release applications

Abstract A microfluidic jet spray drying technique was used to encapsulate hydrophilic drug in uniform microparticles, while tailoring their controlled release functionalities. The effects of different matrix compositions on the release behaviour of a model drug were conducted by spray drying an aqueous polymeric dispersion of a neutral copolymer based on ethyl acrylate and methyl methacrylate (Eudragit® NE) as the main encapsulating matrix. Lactose and silica nanoparticles were used as additives to modify the matrix compositions, with vitamin B12 as the model drug. Evaporation-induced self-assembly of a model drug (vitamin B12) and the matrix materials due to their colloidal interactions produced microparticles with specific morphologies for immediate or prolonged releases. Having lactose distributed homogeneously in the matrix resulted in significantly faster and almost complete release due to enhanced swelling of the polymeric matrix with the dissolution of lactose. In contrast, silica nanoparticles existed mainly at the surface of the particles, due to the slower diffusion of nanoparticles within the droplets upon drying, which could be responsible for the initial burst release of vitamin B12 molecules with erosion of nanoparticles upon contact with the buffer. These outcomes demonstrated the capability to tune the particle response(s) from the knowledge of material properties, with the understanding of release mechanisms elucidated from monodisperse particles of different compositions.

The genome of the obligate endobacterium of an AM fungus reveals an interphylum network of nutritional interactions.

As obligate symbionts of most land plants, arbuscular mycorrhizal fungi (AMF) have a crucial role in ecosystems, but to date, in the absence of genomic data, their adaptive biology remains elusive. In addition, endobacteria are found in their cytoplasm, the role of which is unknown. In order to investigate the function of the Gram-negative Candidatus Glomeribacter gigasporarum, an endobacterium of the AMF Gigaspora margarita, we sequenced its genome, leading to an ∼1.72-Mb assembly. Phylogenetic analyses placed Ca. G. gigasporarum in the Burkholderiaceae whereas metabolic network analyses clustered it with insect endobacteria. This positioning of Ca. G. gigasporarum among different bacterial classes reveals that it has undergone convergent evolution to adapt itself to intracellular lifestyle. The genome annotation of this mycorrhizal-fungal endobacterium has revealed an unexpected genetic mosaic where typical determinants of symbiotic, pathogenic and free-living bacteria are integrated in a reduced genome. Ca. G. gigasporarum is an aerobic microbe that depends on its host for carbon, phosphorus and nitrogen supply; it also expresses type II and type III secretion systems and synthesizes vitamin B12, antibiotics- and toxin-resistance molecules, which may contribute to the fungal host's ecological fitness. Ca. G. gigasporarum has an extreme dependence on its host for nutrients and energy, whereas the fungal host is itself an obligate biotroph that relies on a photosynthetic plant. Our work represents the first step towards unraveling a complex network of interphylum interactions, which is expected to have a previously unrecognized ecological impact.

TiO2-assisted Photocatalytic Degradation of Vitamin B12 in Aqueous Solution:Influencing Factors, Kinetics, and Reaction Investigations

The photodegradation (λ=365 nm) of the biomolecule vitamin B12, catalyzed by the photocatalyst TiO2 nanoparticles (NPs), has been investigated in aqueous suspension. The photodegradation process of vitamin B12 has been monitored by means of electronic absorption (Abs), Fourier-transform infrared (FT-IR), and resonance Raman (RR) spectroscopies, respectively. The results show that only under UV illumination in the presence of TiO2 is there effective degradation, and the photocatalytic degradation of vitamin B12 is strongly influenced by the amount of TiO2 NPs, the pH, and the initial concentration of vitamin B12. The photocatalytic reaction kinetics of vitamin B12 conforms to a Langmuir-Hinshelwood isotherm model. Changes involving the three structural units of the carbon-metal bond C–Co, the organic corrin macrocycle combined with the benzimidazole nucleotide, and the inorganic CN in the vitamin B12 molecule during the photocatalytic degradation are also discussed.

Insulin chewing gum: Need of the day for diabetic patients.

Chewing gum is an excellent drug delivery system for self medication as it is convenient, can be administered discreetly without water and offers the removal of ‘needle fear’ for the patients. As it releases insulin orally, it helps in tackling of the deprivation of insulin by digestive enzyme without adding digestive enzyme inhibitor. This can be done by binding of vitamin B12 and insulin. The vitamin B12 is protected with haptocorrin which is a salivary protein. Another chemical pathway takes over to help vitamin B12 pass into the bloodstream as haptocorrin reaches the intestines. The binding of vitamin B12 and insulin molecules makes the insulin to be protected on this supply chain. The insulin could ride all the way into the bloodstream, where it is released to do its work. By stimulating the brain, chewing gum also increases the releases of insulin. Finding simpler ways to deliver insulin into the blood stream is one important avenue for tackling the diabetes epidemic that is sweeping the developed world. The conditions in gastrointestinal tract may damage the body's protecting and absorbing mechanisms for the valuable molecules. Chewing gum would be a better delivery method in humans.

X-ray absorption near edge structure/electron energy loss near edge structurecalculation using the supercell orthogonalized linear combination of atomic orbitalsmethod

Over the last eight years, a large number of x-ray absorption near edge structure (XANES)and/or electron energy loss near edge structure (ELNES) spectroscopic calculations forcomplex oxides and nitrides have been performed using the supercell-OLCAO (orthogonalizedlinear combination of atomic orbitals) method, obtaining results in very good agreementwith experiments. The method takes into account the core-hole effect and includes thedipole matrix elements calculated from ab initio wavefunctions. In this paper, we describethe method in considerable detail, emphasizing the special advantages of this method forlarge complex systems. Selected results are reviewed and several hitherto unpublishedresults are also presented. These include the Y K edge of Y ions segregated to the core of aΣ31 grain boundary in alumina, O K edges of water molecules, C K edges in different types ofsingle walled carbon nanotubes, and the Co K edge in the cyanocobalamin (vitaminB12) molecule. On the basis of these results, it is argued that the interpretation of specificfeatures of the calculated XANES/ELNES edges is not simple for complex material systemsbecause of the delocalized nature of the conduction band states. The long-standing notionof the ‘fingerprinting’ technique for spectral interpretation of experimental data is nottenable. A better approach is to fully characterize the structure under study, using eithercrystalline data or accurate ab initio modeling. Comparison between calculatedXANES/ELNES spectra and available measurements enables us to ascertain the validity ofthe modeled structure. For complex crystals or structures, it is necessary to use theweighted sum of the spectra from structurally nonequivalent sites for comparison with themeasured data. Future application of the supercell-OLCAO method to complexbiomolecular systems is also discussed.

PH-Responsive, Bolaamphiphile-Based Smart Metallo-Hydrogels as Potential Dye-Adsorbing Agents, Water Purifier, and Vitamin B12 Carrier

A protein amino acid, phenylalanine-based bolaamphiphile 1 containing a centrally located oligomethylene group has been found to be a hydrogelator at nearly physiological pH (pH 6.5−7.2) in the presence of divalent metal salts (such as MnCl2, CoCl2, CuSO4, and NiCl2) on sonication. Other structurally related synthetic bolaamphiphiles 2−4 do not form hydrogels under similar conditions. The metallo-hydrogels have been characterized using transmission electron microscopic (TEM) studies and FT-IR studies. TEM study of these metallo-hydrogels indicates a network of nanofibrilar morphology that might be responsible for gelation. The pH sensitivity of these metallo-hydrogels can be potentially utilized for entrapment and slow release of biologically important molecules. It has been demonstrated that one of these gels entraps and slowly releases vitamin B12 molecules depending upon the pH of the medium. Moreover, these metallo-hydrogels can efficiently adsorb various toxic dyes including Crystal Violet and Naphth...