Question

Which vitamin is incorporated into FAD structure?
A. Vitamin $B_{12}$
B. Vitamin B$_6$
C. Vitamin B$_2$
D. Vitamin C

Answer 1

Hint:FAD is Flavin Adenine Nucleotide, a redox-active coenzyme that is associated with other proteins that take part in various enzymatic reactions and it can exist in four redox states: flavin-N(5)-oxide, quinone, semiquinone, and hydroquinone.

Complete step by step answer: Vitamin B$_2$ is also called riboflavin and is mainly found in eggs, green, vegetables, milk, meat, mushrooms, etc. and has FAD as a cofactor in its two redox states: FAD and FADH$_2$ that is attached to the phosphate group of ADP molecule.
Vitamin $B_{12}$ also known as cobalamin is a cofactor in DNA synthesis, amino acid, and fatty acid metabolism, myelin synthesis, maturation of red blood cells, and exists in chemical forms: cyanocobalamin that is metabolized in the body to form an active coenzyme form, hydroxocobalamin, adenosylcobalamin, and methylcobalamin that are the active cofactor form of vitamin $B_{12}$. Its deficiency leads to pernicious anemia, neuropathy, megaloblasts, myelopathy, etc.
The active form of Vitamin B$_6$ is pyridoxal 5’-phosphate and acts as a coenzyme in amino acid, lipid, and glucose metabolism, and pyridoxal 5’-phosphate oxidase is dependent on Flavin Mononucleotide. Its various forms are Pyridoxine, Pyridoxine 5′-phosphate (P5P), Pyridoxal (PL), Pyridoxal 5′-phosphate (PLP), Pyridoxamine (PM), Pyridoxamine 5′-phosphate (PMP), 4-Pyridoxic acid (PA), and Pyritinol.
Vitamin C is also known as ascorbic acid, is antioxidant and important for skin, bones, and connective tissues as it is a cofactor that helps in healing and allows absorption of iron and its main source is citrus, red and green peppers, tomatoes, broccoli, and greens.
Hence, the correct answer is an option (C).

Note: The enzymatic reaction of formation of FAD starts with the conversion of riboflavin into flavin mononucleotide which is then converted to FAD by FAD synthase and thus, vitamin B$_2$ regulates the availability of FAD.