Defects in cobalamin (B12) metabolism
نویسندگان
چکیده
منابع مشابه
Coenzyme B12 (cobalamin)-dependent enzymes.
The B12 or cobalamin coenzymes are complex macrocycles whose reactivity is associated with a unique cobalt-carbon bond. The two biologically active forms are MeCbl and AdoCbl and their closely related cobamide forms. MeCbl participates as the intermediate carrier of activated methyl groups. During the catalytic cycle the coenzyme shuttles between MeCbl and the highly nucleophilic cob(I)alamin f...
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Vitamin B12 or cobalamin deficiency occurs frequently (> 20%) among elderly people, but it is often unrecognized because the clinical manifestations are subtle; they are also potentially serious, particularly from a neuropsychiatric and hematological perspective. Causes of the deficiency include, most frequently, food-cobalamin malabsorption syndrome (> 60% of all cases), pernicious anemia (15%...
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This review examines deoxyadenosylcobalamin (Ado-B12) biosynthesis, transport, use, and uneven distribution among living forms. We describe how genetic analysis of enteric bacteria has contributed to these issues. Two pathways for corrin ring formation have been found-an aerobic pathway (in P. denitrificans) and an anaerobic pathway (in P. shermanii and S. typhimurium)-that differ in the point ...
متن کاملDisorders of cobalamin (vitamin B12) metabolism: emerging concepts in pathophysiology, diagnosis and treatment.
Although cobalamin (vitamin B12) was isolated almost 60 years ago, its biochemical, physiologic and neurologic effects remain incompletely defined. New observations suggest renal regulation of cobalamin metabolism; actions of cobalamin on nucleic acid and protein function; and a role for cobalamin in cytokine and growth factor regulation. Clinically, no gold standard has emerged for the diagnos...
متن کاملHow I treat cobalamin (vitamin B12) deficiency.
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...
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ژورنال
عنوان ژورنال: Reactome - a curated knowledgebase of biological pathways
سال: 2013
ISSN: 1934-1792
DOI: 10.3180/react_169429.1