Vitamin B12, cobalamin, is a cobalt-containing ring-contracted modified tetrapyrrole that represents one of the most complex small molecules made by nature. In prokaryotes it utilised as cofactor, coenzyme, light sensor and gene regulator yet has restricted role in assisting only two enzymes within specific eukaryotes including mammals. This deployment disparity reflected another unique attribu...

Cobalamin and folate are especially important for women of childbearing age due to their ubiquitous role in fetal growth and development. Population-based data on cobalamin and folate status are lacking from Nepal, where diets are mostly vegetarian. The objectives of the study were to investigate cobalamin and folate intake and status, and to explore associations with socio-demographics, anthro...

In this study, we showed that cyanocobalamin dodecylamine, a ribose 5'-carbamate derivative of cyanocobalamin, was absorbed and accumulated to significant levels by Caenorhabditis elegans and was not further metabolized. The levels of methylmalonic acid and homocysteine, which serve as indicators of cobalamin deficiency, were significantly increased in C. elegans treated with the dodecylamine d...

To investigate the fate of intrinsic factor and cobalamin during cobalamin absorption, we incubated enterocytes isolated from guinea pig ileum for periods of up to 30 min with (57)Co-labeled cyano-cobalamin bound either to human intrinsic factor or to rabbit intrinsic factor biosynthetically labeled with [(35)S]methionine. When the labeled complex was incubated for 30 min with isolated ileal ce...

The marine microalga Ostreococcus is considered to depend on the methionine synthase METH and its methylated cobalamin cofactor for methionine synthesis. Here I describe minimal media lacking both cobalt and cobalamin yet suitable for clonal growth of Ostreococcus tauri. Because Ostreococcus lacks the methylcobalamin-independent methionine synthase METE, Ostreococcus growth without cobalamin is...

The challenges in medical management of cobalamin deficiency lie in attention to the unique pathophysiology that underlies cobalamin deficiency, more than in the mechanics of therapy. The central physiologic principles are that clinically important deficiency is more likely to occur (and progress) when intrinsic factor–driven absorption fails than when diet is poor and that most causes take yea...

Cobalamin deficiency is associated with a wide spectrum of hematologic, neurologic, gastroenterologic and psychiatric disorders or symptoms. We report a case of a 50-year-old man with complex partial seizures with secondary generalization, mood oscillations and psychotic symptoms alternating with confusion and reversible dementia secondary to cobalamin deficiency in the absence of typical neuro...

Cobalamin deficiency in the newborn usually results from cobalamin deficiency in the mother. Megaloblastic anaemia, pancytopenia and failure to thrive can be present, accompanied by neurological deficits if the diagnosis is delayed. Most cases of spina bifida and other neural tube defects result from maternal folate and/or cobalamin insufficiency in the periconceptual period. Polymorphisms in a...

When extracts prepared from cultured human or rodent fibroblasts grown in medium containing [(57)Co]cobalamin were analyzed by polyacrylamide gel electrophoresis, most of the intracellular radioactivity migrated with the activity of the cobalamin-dependent enzyme 5-methyltetrahydrofolate:L-homocysteine S-methyltransferase (EC 2.1.1.13). Because the rodent and human forms of this enzyme are elec...

This review apprises the reader of recent advances in cobalamin absorption and transport since 1970. This field has been of interest to gastroenterologists, hematologists, and biochemists as well as nutritionists. Clinical conditions leading to cobalamin deficiency present especially to the first two of these specialties. Many recent advances involve biochemical definition of the specific trans...