BIOTIN (synonym vitamin H) — the substance neutralizing toxic properties of crude ovalbumin. B. it is important for exchange processes of skin.
In 1901 E. Wildiers established that substance it is necessary for growth of yeast and suggested to call it «biosomes» (from grech, life). In 1935. F. Kogl emitted this substance in a crystal view from a yolk of eggs and suggested to call biotin. P. Gyorgy with sotr. showed that yeast and a number of foodstuff contain the substance protecting rats from intoxication excess of ovalbumin and suggested to call it vitamin H (from it. Haut skin) as at this intoxication integuments are surprised. In 1940 Mr. of P. Gyorgy, etc. pointed out identity of vitamin H and biotin. Same year
V. Vinyo established chemical structure of B. Eto 2'-кето-3,4-имидазолидо-2-тетрагидротиофен-n-валериановая to - that; With 10 H1 6 O 3 N 2 S:
B. represents colourless acicular crystals with t ° pl 230 — 232 °; pier. weight (weight) 244,3; the corner of specific rotation in 0,1 N NaOH solution at t ° 22 ° is equal 92 °. B. we will dissolve in hot water; it is almost insoluble in organic solvents; it is steady against heating; collapses hydrogen peroxide, concentrated acids, caustic alkalis and ultraviolet rays. From 8 stereoisomers B. only D-isomer is biologically active. Biol, activity for a number of microorganisms also derivative B. received by oxidation of sulfur atom (sulfobiotin) and also as a result of replacement of sulfur with oxygen (oxybiotin) or two hydrogen atoms have (desthiobiotin). From amino-acid derivative B. B. connected with a lysine, allocated from yeast and synthesized in 1952 — a growth factor for the majority of bacteria, protozoa, plants, all highest animals and the person is studied biotsitin. It is active in very trace amounts. B. in fabrics it is connected with proteins and peptides. B. participates in several fermental systems catalyzing reactions carboxylation (see). B. participates in biosynthesis fatty acids (see), entering enzyme acetyl to a '-KOA-karboksilazu, catalyzing ATP-dependent synthesis '-SKoA malonyl from CO 2 and '-SKoA acetyl. B. promotes synthesis methionine (see) from serine and a gomotsistein and to accumulation of coenzymatical forms folic to - you. B. it is eurysynusic in the nature (tab.)
In animal products of B. it is connected with proteins, and in vegetables and fruit is in a free look. The main method of definition of B. — microbiological with use of yeast Saccharomyces cerevisiae, Candida, then Lactobacillus casei, Lactobacillus plantarum, Ochromonas danica, etc.
At receipt in an organism with food connected with proteins B. it is chipped off under the influence of proteolytic enzymes and soaked up in small bowels. Whole blood of the person contains from 0,7 to 1,7 mkg of %, in serum — from 0,9 to 1,7 mkg of %, in daily urine — from 29 to 52 mkg of %. It surpasses B.'s arrival with food and is connected with use of bacterial synthesis in intestines, for the account to-rogo a considerable part of need of the person in B is satisfied. It fluctuates from 150 to 200 mkg a day. During pregnancy it raises to 250 — 300 mkg. The main inhibitor B. — avidin (see), contains in ovalbumin. At experimental insufficiency of B. at rats (the diet contained 35% of crude ovalbumin) the termination of growth, falling of weight, reddening and a peeling of skin, baldness of the head, front pads and sides, a spastic gate was observed. Experimental insufficiency of B. was caused in 4 people [V. P. Sydenstricker, 1942] whose 30% of caloric content of a diet were made by crude ovalbumin. In 9 — 10 weeks desquamative dermatitis, a depression, weakness, drowsiness, muscular pains, later — anorexia, nausea, slight anemia, increase in content of cholesterol in blood serum, decrease in allocation of B. with urine to 3,5 — 7,3 mkg was observed. After B.'s injections in doses of 75 — 300 mkg a day these disturbances were liquidated within 3 — 5 days, B.'s allocation with urine to 55 mkg a day increased. Cases of insufficiency of B. at the people consuming large numbers of crude eggs are rare; they are described in 1942 by R. H. AVilliams and in 1968 Bo (S. M. Baugh). Disturbances of exchange and B.'s insufficiency are observed at seborrheal dermatitis at babies (Leyner's disease), at a diabetes mellitus, acute and hron, hepatitises. B.'s appointment on 400 mkg a day prevented development of cholesteric atherosclerosis in rabbits. Medical doses of B. reduced the content of the general cholesterol and β-lipoproteids in blood at patients with atherosclerosis, and also reduced release of thiamin and ascorbic to - you.
B. I. Titov in 1966 established decrease in maintenance of B. in blood at the elderly people sick with atherosclerosis and a hypertension, and recommended its preventive use. B. in animal experiments has no toxic effect even in considerable doses.
Bibliography: Hygiene of food, under the editorship of. K. S. Petrovsky, t. 1, page 142, M., 1971 Likhtsiner N. B. Biotin and his insufficiency, Mnogotomn. the management on vnutr. Bol., under the editorship of E. M. Tareev, t. 8, page 659, M., 1965; Baker H. Clinical vitaminology, N. Y. — L., 1968; Baugh C. M, Malone J. H. a. Butter-worth G.E. Human biotin deficiency, Amer. J. clin. Nutr., v. 21, p. 173, 1968, bibliogr.; G at orgy P. Biotin, in book: Vitamins, ed. by W. H. Sebrell a. R. S. Harris, v. 1, p. 527, N. Y., 1954, bibliogr.; Mistry S. P. a. Dakshinamur-t i K. Biochemistry of biotin, Vitam. and Horm., v. 22, p. 1, 1964, bibliogr.; T e γ-γο i n e T. Physiology and biochemistry of biotin, ibid., v. 18, p. 1, 1960, bibliogr.
V. V. Efremov.