Vitamin C of mannose or galactose to ascorbic acid. In animals, the starting material is glucose. In some species that synthesize ascorbate in the liver (including mammals and perching birds), the glucose is extracted from glycogen; ascorbate synthesis is a glycogenolysis-dependent process. In animals that cannot synthesize vitamin C, the enzyme -gulonolactone oxidase (GULO), that catalyses the last step in the biosynthesis, is highly mutated and non-functional. The biosynthesis of ascorbic acid in vertebrates starts with the formation of UDP-glucuronic acid. UDP-glucuronic acid is formed when UDP-glucose undergoes two oxidations catalyzed by the enzyme UDP-glucose 6-dehydrogenase. UDP-glucose 6-dehydrogenase uses the co-factor NAD
Vitamin B12 "Corynebacterium", "Flavobacterium", "Lactobacillus", "Micromonospora", "Mycobacterium", "Nocardia", "Protaminobacter", "Proteus", "Rhizobium", "Salmonella", "Serratia", "Streptococcus" and "Xanthomonas" . Six Nobel Prizes have been awarded for direct and indirect studies of vitamin B. Vitamin B12 Vitamin B, also called cobalamin, is a water-soluble vitamin that is involved in the metabolism of every cell of the human body: it is a cofactor in DNA synthesis, and in both fatty acid and amino acid metabolism. It is particularly important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the maturation of developing red blood cells in the