niacin

Nicotinic acid is also known as niacin or anti-skin factor. Nicotinic acid is rich in liver, lean meat, poultry, peanuts and yeast in food, and the content of niacin and tryptophan in various cereals is low. Nicotinic acid generates nicotinamide through transamination. Nicotinamide reacts with phosphoribosyl pyrophosphate to form nicotinamide mononucleotide, which combines with ATP to form nicotinamide adenine dinucleotide (NAD). Also called coenzyme I (CoI). NAD and adenosine triphosphate (ATP) combine to form nico-tinamide adenine dinucleotide phosphate (NADP), also known as coenzyme Ⅱ (CoⅡ). In many anaerobic dehydrogenases, NAD and NADP function as dehydrogenase coenzymes. NAD and NADP are the main coenzymes of the redox reaction system during cell metabolism. In addition to food sources, niacin can also be converted from tryptophan, which first becomes kynurenine. Tryptophan pyrithase and formylase are needed. It hydrolyzes formyl kynurenine to kynurenine, and then 1-kynuric acid hydrolase decomposes kynuric or xanuric acid into 3-hydroxyaminobenzoic acid. Under the action of 5-phosphate ribose pyrophosphate, the enzyme system of mammalian liver becomes niacin. The metabolized products of niacin are N'-methylnicotinamide and N'-methyl-2-pyridone-5-carboxamide. The former is 20% to 30% of urine excretion and the latter is urine. Excretion of 40% to 60%.