Chapter title |
Biochemistry of B12-Cofactors in Human Metabolism
|
---|---|
Chapter number | 17 |
Book title |
Water Soluble Vitamins
|
Published in |
Sub cellular biochemistry, February 2016
|
DOI | 10.1007/978-94-007-2199-9_17 |
Pubmed ID | |
Book ISBNs |
978-9-40-072198-2, 978-9-40-072199-9
|
Authors |
Bernhard Kräutler, Kräutler, Bernhard |
Abstract |
Vitamin B12, the "antipernicious anaemia factor", is a crystallisable cobalt-complex, which belongs to a group of unique "complete" corrinoids, named cobalamins (Cbl). In humans, instead of the "vitamin", two organometallic B12-forms are coenzymes in two metabolically important enzymes: Methyl-cobalamin, the cofactor of methionine synthase, and coenzyme B12 (adenosyl-cobalamin), the cofactor of methylmalonyl-CoA mutase. The cytoplasmatic methionine synthase catalyzes the transfer of a methyl group from N-methyl-tetrahydrofolate to homocysteine to yield methionine and to liberate tetrahydrofolate. In the mitochondrial methylmalonyl-CoA mutase a radical process transforms methylmalonyl-CoA (a remains e.g. from uneven numbered fatty acids) into succinyl-CoA, for further metabolic use. In addition, in the human mitochondria an adenosyl-transferase incorporates the organometallic group of coenzyme B12. In all these enzymes, the bound B12-derivatives engage (or are formed) in exceptional organometallic enzymatic reactions. This chapter recapitulates the physiological chemistry of vitamin B12, relevant in the context of the metabolic transformation of B12-derivatives into the relevant coenzyme forms and their use in B12-dependent enzymes. |
Mendeley readers
Geographical breakdown
Country | Count | As % |
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United States | 1 | <1% |
Unknown | 109 | 99% |
Demographic breakdown
Readers by professional status | Count | As % |
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Student > Bachelor | 18 | 16% |
Student > Ph. D. Student | 17 | 15% |
Researcher | 11 | 10% |
Student > Master | 9 | 8% |
Student > Doctoral Student | 6 | 5% |
Other | 14 | 13% |
Unknown | 35 | 32% |
Readers by discipline | Count | As % |
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Nursing and Health Professions | 6 | 5% |
Other | 9 | 8% |
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