Vitamin C and copper atoms in their reduced states. Vitamin C acts as an electron donor for eight enzymes: The name "vitamin C" always refers to the -enantiomer of ascorbic acid and its oxidized forms, such as dehydroascorbate (DHA). Therefore, unless written otherwise, "ascorbate" and "ascorbic acid" refer in the nutritional literature to -ascorbate and -ascorbic acid respectively. Ascorbic acid is a weak sugar acid structurally related to glucose. In biological systems, ascorbic acid can be found only at low pH, but in solutions above pH 5 is predominantly found in the ionized form, ascorbate. All of these molecules have vitamin C
Vitamin B6 pyridoxal and pyridoxamine. Vitamin B was named pyridoxine to indicate its structural homology to pyridine. Vitamin B6 Vitamin B refers to a group of chemically similar compounds which can be interconverted in biological systems. Vitamin B is part of the vitamin B group of essential nutrients. Its active form, pyridoxal 5′-phosphate, serves as a coenzyme in some 100 enzyme reactions in amino acid, glucose, and lipid metabolism. All forms except pyridoxic acid and pyritinol can be interconverted. Absorbed pyridoxamine is converted to PMP by pyridoxal kinase, which is further converted to PLP by pyridoxamine-phosphate transaminase or pyridoxine 5′-phosphate oxidase which