Biochemistry

2e), but only one H + atom is attached to the coenzyme molecule, and the second gives an electron to the coenzyme and turns into a proton. The lack or deficiency of nicotinic acid leads to a disorder of coenzymes of dehydrogenases synthesis, and accordingly, to a disorder of redox reactions, to a disorder of cellular respiration. Niacin has a regulatory effect on the central nervous system, hematopoiesis, digestive and cardiovascular systems (in particular, it dilates peripheral vessels, improves cholesterol metabolism). Niacin deficiency. Inadequate intake of vitamin PP in the body leads to various disorders. In the initial stage of PP-vitamin deficiency, general symptoms are noted: weakness, apathy, insomnia, dizziness, etc. In the future, the development of pellagra is possible. An expanded picture of pellagra can be characterized by a symptom complex of three "D" - diarrhea, dermatitis, and dementia. Appetite decreases, salivation increases, tongue increases (swollen, with teeth imprints), a burning sensation appears, the papillae atrophy, it becomes “ lacquered ” . The secretory and motor function of the gastrointestinal tract is disturbed, abdominal pain, diarrhea occurs. In open areas of the skin appear puffiness, redness, and sometimes ulcers (dermatitis). The functions of the nervous system are disturbed, a mental disorder (dementia) is noted. Daily intake of vitamin PP is 15-25 mg. The need for it increases with heavy physical exertion, for example, among workers in hot shops, intense neuropsychic activity, when working with substances that have a toxic effect on the functions of the skin, liver, as well as diseases of the cardiovascular system, gastrointestinal tract, hematopoietic organs. The need for vitamin PP increases in pregnant and lactating women, with low-protein nutrition and the predominance of vegetable proteins in the diet. Sources. Rich sources of vitamin PP are liver, beef, pork, and lamb. Milk and dairy products are poor in niacin, but they contain significant quantities of tryptophan, a source of endogenous synthesis of nicotinic acid. The main sources of vitamin PP among plant products are bakery and cereal products, especially bran and yeast. Pantothenic acid (vitamin B 3 ). The name of this vitamin (from the greek. panthoten - everywhere) indicates its widespread occurrence in nature. Pantothenic acid was first isolated from yeast and liver extract in 1938. In 1940, it was possible to decipher its chemical structure and synthesize. Structure and physicochemical properties. Vitamin B 3 is a compound of 0- alanine with a, ү -dihydrooxy-P-dimethyl butyric acid. 255