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ACYLATION — substitution in a molecule of organic compound of hydrogen atom or metal acyl, i.e. the rest of an organic molecule to - you; plays a large role in a metabolism (e.g., synthesis of fatty acids, proteins). Special case And. acetylation, i.e. substitution of hydrogen atom is a monovalent radical (rest) acetic to - you. In an organism of reaction And. proceed with participation of special substance — a coenzyme of acylation of KoA-SH (see. Coenzymes ). Acid is activated by connection with the sulphhydryl KoA-SH group in the beginning, acyl-S-KoA is formed. This reaction proceeds with use of energy of an energy-rich bond adenosine triphosphoric to - you are (ATP). The rest of acid then is postponed with acyl-S-KoA to the acylated substance. In such way there is, e.g., an accession of the remains of fatty acids (stearin, etc.) to phosphoglycerol to - those in the course of synthesis of fats: 1) KOA - SH + stearin to - that + ATP → stearyl-S-KoA + ADF + pyrophosphoric to - that; 2) stearyl-S-KoA + phosphoglycerol to - that → stearylphosphoglycerol to - that + KoA-SH. In processes of a metabolism

the active form acetic to - you — acetyl-S-KoA is essential, edges it is formed at aerobic disintegration of carbohydrates, amino acids, fatty acids; on the other hand, acetyl-S-KoA participates in synthesis of various substances, including fatty acids and amino acids. Thus, it turns out acetyl-S-KoA a link, in Krom pathways of the main components of an organism cross. Two molecules acetyls-S-KoA can interact with education acetoacetyl-S-KoA; this connection breaks up on acetoacetic to - that and KoA-SH.

And. apply in pharmaceutical industry at synthesis of a number of medicinal substances. In an organism by means of reactions And. there is a neutralization and release of substances poisonous or unusual for an organism. E.g., the benzoic to - that is neutralized in a liver by education benzaminoacetic to - you. In the beginning it is formed benzoyl-S-KoA, to-ry acylates glycine with education benzaminoacetic to - you. The functional trial of Kvik is based on this property of a liver. Many medicinal substances (streptocides, Ftivazidum, PASK, etc.) are in large part removed from an organism in the form of acetyl derivatives.

To reactions biological And. belongs as well biosynthesis proteins (see). KOA does not participate in this reaction; amino acid is activated software a carboxyl group by formation of anhydrite communication with adenylic to - that (see. Adenozinfosforny acids ). The activated amino acid acylates other amino acid on an amino group therefore the peptide bond is formed.

See also Metabolism and energy , biological oxidation .

Bibliography: Filippovich Yu. B. Fundamentals of biochemistry, M., 1969; Shmelyov N. A., Kozulitsyna T. I. and Smirnov of G. A. Problem of a bystry inactivation of Ftivazidum in an organism of TB patients, Probl. tube., No. 6, page 32, 1961 · Yurkevich A. M., Severin E. S. and Braunstein A. E. Organic cofactors of enzymes — coenzymes, in book: Enzymes, under the editorship of A. E. Braunstein, page 147, M., 1964, bibliogr.

A. Ya. Nikolaev.