Neovitamin B12 (cyano-13-epicobalamin)
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چکیده
(3-Epimerization in the corrinoid system has recently emerged as a complicating factor in the latter stages of the total synthesis of vitamin B12 (Eschenmoser 1971; Woodward 1973). I t has also found some application in biosynthetic studies on the origin of the methyl groups in ring C (Scott, Townsend & Cushley 1973; Scott, this Discussion p. 303). This paper sets out to review briefly the (3-epimerization of corrinoid polyamides, with particular reference to our work on the neo-series which provided the first established example of this phenomenon.
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Neovitamin B12 (cyano-13-epicobalamin)
(3-Epimerization in the corrinoid system has recently emerged as a complicating factor in the latter stages of the total synthesis of vitamin B12 (Eschenmoser 1971; Woodward 1973). I t has also found some application in biosynthetic studies on the origin of the methyl groups in ring C (Scott, Townsend & Cushley 1973; Scott, this Discussion p. 303). This paper sets out to review briefly the (3-e...
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Reduced ferredoxin is capable of reducing nonenzymatitally cyano-Bit. Spectral studies have shown that BE, (a l-electron reduced derivative of the vitamin) accumulates in the reaction although the formation of methyl-B12 was observed upon the addition of methyl iodide to the incubation. The data indicate that reduction of cyano-Blz by reduced ferredoxin results in the transient formation of B12...
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A consideration of numerous studies in viva indicates that the metabolism of methionine, folic acid, and cyano-B1$ is interrelated. The vitamin has a sparing effect on the methyl group requirement of young chickens, and, conversely, methionine has a sparing effect on the cyano-Blz requirement in chickens and rats (l-4). A more direct demonstration of an impairment in methyl group biosynthesis d...
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Studies by several investigators (Stokstad, Dornbush, Franklin, Hoffmann, Hutchings, and Jukes, 1949; Skeggs, Nepple, Valentik, Huff, and Wright, 1950) have indicated that an increased growth response was obtained to liver concentrates with thioglycolic or thiomalic acids when vitamin B12 activity was determined with Lactobacillus leichmannii. This was attributed to the prevention, by such redu...
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