B12 10mg (10ml)

Vitamin B12 (cobalamin) is a cobalt-containing tetrapyrrolic micronutrient that serves as an essential cofactor for two mammalian enzymes: methionine synthase (which transfers a methyl group to homocysteine to regenerate methionine) and L-methylmalonyl-CoA mutase (a mitochondrial enzyme that isomerizes methylmalonyl-CoA to succinyl-CoA during propionate metabolism). B12 deficiency produces well-characterized hematological and neurological phenotypes that have been studied for more than a century in the published medical and biochemical literature.

This research-supply preparation provides cobalamin at 10 mg per 10 mL in an aqueous vehicle. The "B12" label encompasses several chemically distinct cobalamin forms: cyanocobalamin (the stable synthetic form historically used in injections and supplementation), hydroxocobalamin (used in cyanide-poisoning research and clinical settings), methylcobalamin (the cofactor form for methionine synthase), and 5'-deoxyadenosylcobalamin (the cofactor form for methylmalonyl-CoA mutase). Suppliers typically specify which cobalamin form is provided on the certificate of analysis; assume methylcobalamin or cyanocobalamin unless otherwise noted.

This page is a research-only educational reference. The preparation is supplied for laboratory and research-supply use and is not intended for human consumption or any therapeutic application. No medical claims are made on this page.

Cobalamin is a corrin-ring tetrapyrrole coordinating a central cobalt atom, with a 5,6-dimethylbenzimidazole "lower ligand" coordinating one axial position of the cobalt and a variable "upper ligand" (cyano, hydroxo, methyl, or 5'-deoxyadenosyl) defining the specific cobalamin form. The molecule is large for a vitamin (~1,355 Da for cyanocobalamin) and is the only mammalian vitamin that contains a metal ion. Cobalamin biosynthesis is restricted to bacteria and archaea; mammals — including humans — obtain B12 from dietary sources of microbial origin (animal tissues that accumulate microbial B12, fermented foods, and supplementation).

A 10 mg / 10 mL aqueous research preparation corresponds to 1 mg/mL cobalamin. The standard reference dose for clinical B12 replacement is in the 1 mg range, so a 10 mL vial at this concentration contains roughly ten reference-dose equivalents; however, this preparation is supplied for research-supply use and the reference is provided only for chemical orientation, not as a dosing instruction.

The methylcobalamin and 5'-deoxyadenosylcobalamin coenzyme forms are light-sensitive and are typically protected from light during storage. Cyanocobalamin is substantially more photostable and is the form most commonly used in long-term liquid preparations. Hydroxocobalamin is intermediate in stability and is the precursor that the body converts to the active coenzyme forms in tissues.

This is a small-molecule vitamin cofactor, not a peptide. It is included in research-supply catalogs alongside peptide research compounds because of its widespread use in metabolic and neurological research and its frequent inclusion in combination preparations (Lipo-C, MIC blends, etc.).

Cobalamin was identified through more than fifty years of work on pernicious anemia, a fatal megaloblastic anemia first described clinically by Thomas Addison in the 1850s. George Whipple, George Minot, and William Murphy demonstrated in 1926 that feeding raw liver reversed the anemia, work that received the 1934 Nobel Prize in Physiology or Medicine. The active factor was isolated in 1948 simultaneously by Edward Rickes and colleagues at Merck and by E. Lester Smith at Glaxo, who crystallized red cobalt-containing compounds from liver extracts. Dorothy Hodgkin determined the three-dimensional structure of cyanocobalamin by X-ray crystallography in 1956 — work that contributed to her 1964 Nobel Prize in Chemistry — revealing the corrin ring and central cobalt atom.

The two mammalian B12-dependent enzymes were characterized over subsequent decades. Methionine synthase, a cytosolic enzyme using methylcobalamin as the methyl-transfer cofactor, was characterized for its role in one-carbon metabolism and the regeneration of methionine from homocysteine. L-methylmalonyl-CoA mutase, a mitochondrial enzyme using 5'-deoxyadenosylcobalamin in a radical-based isomerization, was characterized for its role in propionate metabolism (oxidation of odd-chain fatty acids, branched-chain amino acids, and other propionate sources).

The intrinsic-factor pathway for cobalamin absorption — gastric parietal-cell intrinsic factor binding cobalamin in the small intestine, receptor-mediated uptake at the ileal brush border, and transcobalamin-II-mediated delivery to tissues — was characterized through the 1960s-1980s and explains the autoimmune-gastritis basis of classical pernicious anemia. Genetic disorders of intracellular cobalamin metabolism (cblA-cblG, the cobalamin complementation groups) were characterized through the 1970s-2000s and continue to inform fundamental cobalamin biochemistry.

Mammalian cobalamin biochemistry centers on two coenzyme functions. First, methylcobalamin serves as the methyl-carrying cofactor for methionine synthase (MTR), a cytosolic enzyme that transfers a methyl group from 5-methyltetrahydrofolate onto homocysteine to produce methionine and tetrahydrofolate. This reaction couples the folate one-carbon cycle to the methionine cycle and is the only reaction in mammals that recycles 5-methyltetrahydrofolate back to tetrahydrofolate. Loss of methionine synthase activity — through B12 deficiency, MTR mutations, or nitrous-oxide oxidation of the enzyme's cobalt — produces "methyl-trap" folate sequestration, elevated homocysteine, and impaired methionine and S-adenosylmethionine (SAM) synthesis.

Second, 5'-deoxyadenosylcobalamin serves as the radical-generating cofactor for L-methylmalonyl-CoA mutase (MUT), a mitochondrial enzyme that isomerizes L-methylmalonyl-CoA to succinyl-CoA. This reaction is the third step of propionate catabolism (after propionyl-CoA carboxylase and methylmalonyl-CoA epimerase) and is the gateway for entry of propionate-derived carbon into the citric-acid cycle. Loss of MUT activity — through B12 deficiency, MUT mutations, or impaired adenosylcobalamin synthesis — produces methylmalonic-acid accumulation and the methylmalonic-acidemia clinical syndromes.

Cobalamin pharmacokinetics in mammals depend on the intrinsic-factor / transcobalamin pathway for oral absorption, but intramuscular or subcutaneous administration bypasses this requirement. Tissue uptake is mediated by transcobalamin-II receptors on most cell types. Intracellular processing converts the entering cobalamin form (cyano, hydroxo, methyl, or adenosyl) into the two coenzyme forms required by MTR and MUT via the cobalamin-processing pathway encoded by the cblA-cblG genes.

The B12 / folate / methionine / SAM axis is central to one-carbon metabolism research, which intersects with epigenetics (SAM as the methyl donor for DNA and histone methyltransferases), redox biology (cysteine and glutathione synthesis through the transsulfuration arm), and neurological function (homocysteine elevation as a risk biomarker for various conditions). Research applications of B12 preparations span enzyme kinetics, cell-culture media supplementation, deficiency-model induction (typically through nitrous-oxide exposure or dietary restriction in rodents), and combination-preparation research (Lipo-C blends containing B12, methionine, inositol, and choline).

The methylcobalamin versus cyanocobalamin distinction is a frequent point of confusion. Both forms ultimately enter the same intracellular cobalamin-processing pathway and produce the same two coenzyme forms (methylcobalamin and adenosylcobalamin) used by MTR and MUT. The practical differences are photostability (cyanocobalamin is substantially more stable) and the initial intracellular processing step required (cyanocobalamin requires decyanation; methylcobalamin enters the methylcobalamin pool directly but is then partially demethylated to feed the adenosylcobalamin pool). Clinical and research literature does not consistently demonstrate superiority of one form over the other for replacing systemic B12 stores.

Cobalamin is a corrinoid: a corrin macrocycle (four reduced pyrrole rings linked by three methylene bridges and one direct C-C bond) coordinating a central cobalt atom. The lower axial position of the cobalt is coordinated by a 5,6-dimethylbenzimidazole nucleotide tethered to the corrin ring via an aminopropanol linker and a phosphodiester bond. The upper axial position carries the variable "ligand" that defines the specific cobalamin form: -CN (cyanocobalamin), -OH (hydroxocobalamin), -CH3 (methylcobalamin), or -5'-deoxyadenosyl (5'-deoxyadenosylcobalamin, also called coenzyme B12 or adenosylcobalamin).

Molecular weights: cyanocobalamin ~1,355 Da; hydroxocobalamin ~1,346 Da; methylcobalamin ~1,344 Da; adenosylcobalamin ~1,580 Da. All forms are intensely red colored due to charge-transfer absorption in the visible spectrum involving the corrin π-system and the cobalt center.

The 10 mg / 10 mL aqueous preparation provides cobalamin at 1 mg/mL. Aqueous cobalamin solutions are typically stored refrigerated and protected from light. Methylcobalamin solutions are particularly photolabile and may convert to hydroxocobalamin under light exposure. Vial integrity, sterility, and pH are standard quality parameters for a research-supply liquid preparation.

In published research, cobalamin preparations are used in several principal contexts:

Enzyme kinetics and mechanistic studies. Purified methionine synthase and methylmalonyl-CoA mutase are studied with cobalamin coenzyme forms to characterize substrate binding, reaction mechanism (the radical-based isomerization of MUT, the methyl-transfer chemistry of MTR), inhibition (by nitrous oxide, by methyl-transferase inhibitors), and reactivation kinetics. These are biochemical research applications using purified proteins and defined cofactor preparations.

Cell-culture media supplementation. Many commercial cell-culture media contain cobalamin at micromolar concentrations to support cell-autonomous one-carbon metabolism. Research-supply B12 is used to formulate custom media for studies of cobalamin-dependent metabolism, methyl-cycle perturbation, and folate-cobalamin interactions.

Deficiency-model induction in rodents. Rodent cobalamin-deficiency models can be induced by dietary restriction (cobalt-deficient or B12-restricted diets), by nitrous-oxide exposure (which oxidizes the cobalt of methionine synthase and inactivates the enzyme), or by genetic models targeting cobalamin-processing genes. B12 preparations are used both as the deficient nutrient (in restriction protocols) and as the repletion intervention to characterize recovery kinetics.

One-carbon metabolism research. The B12-folate-methionine-SAM axis is studied in the context of epigenetic regulation (SAM-dependent methylation), redox biology (transsulfuration and glutathione synthesis), neural-tube-defect research, and homocysteine-related cardiovascular research. B12 preparations are a standard tool in this research area.

Combination preparation research. Cobalamin appears as a component of multi-ingredient research preparations such as Lipo-C / MIC blends (methionine + inositol + choline + B12) used in metabolic research, and in formulation development for parenteral nutrition.

Bacterial cobalamin biosynthesis research. The biosynthesis pathway is among the most complex in biochemistry (~30 enzymes), and cobalamin preparations of defined upper-ligand form are used as standards and substrates in microbial-biosynthesis research.

Cobalamin-corrinoid analog research. Research on cobalamin analogs (corrinoids with non-DMB lower ligands, alternative upper ligands, and synthetic modifications) uses the parent cobalamin as the reference standard.

All applications are research-supply context: laboratory and analytical use in cells, isolated enzymes, and rodent in-vivo studies. The compound is not for human consumption in this research-supply context. Nothing on this page describes a clinical protocol or therapeutic use.

Cobalamin sits at the intersection of vitamin biochemistry, one-carbon metabolism, and clinical hematology. The principal cobalamin forms and adjacent compounds are summarized below.

Vitamin B12 (cobalamin) is a cobalt-containing corrinoid micronutrient that serves as the cofactor for two mammalian enzymes: cytosolic methionine synthase (using methylcobalamin) and mitochondrial methylmalonyl-CoA mutase (using 5'-deoxyadenosylcobalamin). Loss of either function — through B12 deficiency, enzyme mutation, or cofactor oxidation — produces well-characterized hematological and neurological phenotypes that have shaped a century of medical and biochemical literature.

This 10 mg / 10 mL aqueous preparation provides cobalamin for research-supply use: enzyme kinetics, cell-culture media formulation, rodent deficiency-model studies, one-carbon-metabolism research, and combination-preparation development. The specific cobalamin form (methyl, cyano, hydroxo, or adenosyl) determines photostability and direct cofactor activity, but all forms feed the same intracellular cobalamin-processing pathway.

The preparation is supplied as a research-supply chemical, not as a medicine. There are no medical claims on this page, and the information is provided strictly for research-context biochemical and educational orientation.