METABOLITES (grech, metabole change, transformation) — the substances which are exposed to chemical turning into an organism in the course of an intermediate metabolism of substances (metabolism).
Due to any operation of regulatory mechanisms dynamic concentration of M. in a healthy organism are maintained on the fixed level characteristic of each M. Average sizes of these concentration (with the indication of limits of fluctuations) serve one of characteristics of norm. At patol, conditions of concentration of M. change, and these changes often happen specific to this or that disease. Many are based on it biochemical, methods a lab. diagnoses of diseases.
Many M. come to an organism from the outside as a part of food and are predecessors of other M. which are formed in an organism. Substances in living cell consistently turn at first into one M., from to-rogo another is formed, etc. Such sequences of transformations are called in the metabolic ways. E.g., the metabolic way of disintegration of glucose to lactic acid includes such sequence of M.: glucose —> glyukozo-6-phosphate —> fruktozo-6-phosphate —> fruktozo-1,6-diphosphate —> phosphoglyceric aldehyde 1,3-diphosphoglyceric to - that is> phosphoenolpyruvic to - that is> Pyroracemic to - that is> milk to - that. Each metabolite is formed of the predecessor as a result of effect of specific enzyme and, in turn, serves as substrate for other enzyme (see. Enzymes ). Selective interruption of metabolic chains with the help is based on it antimetabolites (see) — structural analogs of metabolites, to-rye are used as pharmaceuticals, and also in pilot studies.
In the course of metabolism M. which are structurally functional components of a cell, napr such as coenzymes, hormones and other regulatory substances, proteins, nucleinic to - you, structural polysaccharides etc. are formed. It should be noted, however, that the term «metabolites» to high-molecular substances is applied seldom. M can turn into end products of a metabolism (final M.) brought out of an organism. The main final M. for many animals and the person are carbonic acid (CO 2 ), water, urea (at reptiles and birds instead of urea it is formed uric to - that). Final M.' number, including M. of alien connections, is removed in the form of glucuronides, sulfates, products of mikrosomny oxidation.
Cells of different types of animals have both similarity, and distinctions on M.'s structure E.g., amino acids, nucleotides, many coenzymes, etc. are universal for all life forms. On the contrary, M., being predecessors of irreplaceable food factors of the person — vitamins, irreplaceable amino acids, irreplaceable fat to - t, etc., are absent in a human body, but are available for many microorganisms, plants and nek-ry animals capable to synthesize these substances,
See also Metabolism and energy .
A. Ya. Nikolaev.