Vitamin C biosynthesis

Conklin PL, Norris SR, Wheeler GL et al (1999) Genetic evidence for the role of GDP-mannose in plant ascorbic acid (vitamin C) biosynthesis. Proc Natl Acad Sci USA 96 4198-4203... 

Linster CL, Van Schaftingen E. Vitamin C Biosynthesis, recycling and degradation in mammals. PEBS J. 2007 274 1-22. 

Humans, in common with other primates, are incapable of vitamin C biosynthesis. For that reason, this nutrient must be obtained from dietary sources. Vitamin C is well known to be essential for capillary and blood... 

The vast majority of animals and plants are able to synthesize vitamin C through a sequence of four enzyme-driven steps, which convert D-glucose to vitamin C (Fig. 12.6). In eukaryotes, vitamin C biosynthesis occurs via two highly divergent biochemical pathways. In rats and other mammals, glucose is converted into L-gulono-1,4-lactone via a complex pathway involving uronic acid derivatives and... 

Banta S, Swanson BA, Wu S, Jamagin A, Anderson S (2002) Optimizing an artificial metabolic pathway engineering the cofactor specificity of Corynebacterium 2,5-diketo-D-gluconic acid reductase for use in vitamin C biosynthesis. Biochemistry 41 6226-6236 Bremus C, Herrmann U, Biinger-Meyer S, Sahm H (2006) The use of microorganisms in L-ascorbic acid production. J Biotechnol 124 196-205... 

Metabolic engineering of Kluyveromyces lactis for L-ascorbic acid (vitamin C) biosynthesis. Microb. 

Valonia, cellulose, 326, 329-330 Vitamin B6, biosynthesis, 1-deoxy-D-threo-pentulose in, 287 Vitamin C... 

The complex series of events in collagen maturation provide a model that illustrates the biologic consequences of incomplete polypeptide maturation. The best-known defect in collagen biosynthesis is scurvy, a result of a dietary deficiency of vitamin C required by... 

The formation of Hyp and Hyl residues in procollagen is catalyzed by iron-containing oxygenases ( proline and lysine hydroxylase, EC 1.14.11.1/2). Ascorbate is required to maintain their function. Most of the symptoms of the vitamin C deficiency disease scurvy (see p. 368) are explained by disturbed collagen biosynthesis. 

Pharmacology Vitamin C, a water-soluble vitamin, is an essential vitamin in man however, its exact biological functions are not fully understood. It is essential for the formation and the maintenance of intercellular ground substance and collagen, for catecholamine biosynthesis, for synthesis of carnitine and steroids, for conversion of folic acid to folinic acid and for tyrosine metabolism. 

Vitamin C, ascorbic acid, is required as a cofactor for the enzyme prolyl hydroxylase, which catalyzes the formation ofhydroxyproiine during collagen biosynthesis. 

Like folate and vitamin C, vitamin B6 (pyroxidine) is water soluble and like folate has several vitamers. Vitamin B6 may be involved in more bodily functions than any other nutrient (Tambasco-Studart et al., 2005), is a cofactor for many enzymes, especially those involved in protein metabolism, and is also a cofactor for folate metabolism. Vitamin B6 has anticancer activity (Theodoratou et al., 2008), is a strong antioxidant (Denslow et al., 2005), is involved in hemoglobin biosynthesis, lipid and glucose metabolism and immune and nervous system function. Possible consequences of deficiency include anemia, impaired immune function, depression, confusion, and dermatitis (Spinneker et al., 2007). Vitamin B6 deficiency is generally not a problem in the developed world, but there could be as yet poorly defined consequences of suboptimal intake particularly for the elderly. 

Woodward-Eschenmoser method, 4, 431-440 neo-Vitamin B12, 4, 421 Vitamin C — see Ascorbic acid Vitamin E—see a-Tocopherol Vitamin K epoxide, 7, 119 synthesis, 1, 439 Vitamins heterocyclic biosynthesis, 1, 90-108 as pharmaceuticals, 1, 154-156 in synthesis reviews, 1, 67 Vogeletin synthesis, 3, 716... 

The current RDA for vitamin C is 60 mg/day for a healthy non-smoking adult, Vitamin C is a cofactor for several enzymes involved in the biosynthesis of collagen, neurotransmitters, carnitine (45), hydroxylation of cholesterol (to form bile acids). It is also an important water-soluble antioxidant, which scavenges most of the RS and acts as a coantioxidant by regenerating a-tocopheryl radicals (46). 

In the context of a chemical study related to problems of vitamin B12 biosynthesis, peripheral C-methylation of the magnesium complex of tctct-OEPc (17) was reported to yield a mixture of isomeric products (18a-c) (83AG(E)631). A similar reaction was found to occur at C-12 of nonamethyl pyrrocorphin (19). One of the by-products of this reaction is the seco-corphinoid derivative 20, which, on complexation with Ni(II) acetate, cyclizes to give an Ni(II) corrinate (21) (84CC583). 

Wolucka, B.A., and Van Montagu, M., 2003, GDP-Mannose 3, 5 -epimerase forms GDP-L-gulose, a putative intermediate for the de novo biosynthesis of vitamin C in plants. J. Biol. Chem. 278 47483-47490. 

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