From Big Medical Encyclopedia

METALLOPROTEINS — complex proteins, a nonprotein part of a molecule to-rykh it is presented by ions of metals, and these ions are a component of structure of proteinaceous molecules and cannot be allocated without destruction of this structure. Many enzymes (see) represent M., in molecules to-rykh an ion of metal participates in linkng of enzyme with substrate, i.e. provides chelation or directly carries out catalytic function, being a part of the active (catalytic) center of enzyme. Biol, value M. is extremely big since they define normal functioning of the vital links of a metabolism in an organism of animals and the person, and also in vegetable organisms and microorganisms.

Ferriferous M. transport oxygen in fabric (see. Gemoglobin , Mioglobin ), participate in mitochondrial electron transfer (see. Tsitokhroma ), decomposition of hydrogen peroxide (see. Catalase ), deposition of iron (see. Ferritin ), regulate redoxreactions in the course of cellular respiration, photosynthesis, nitrogen fixation (a ferredoksina, specific protein of purple bacteria). In ensuring processes of life activity cupriferous M. are important (see. Copper , Tyrosinase ). Tsinksoderzhashchiye M. carry out disintegration coal to - you to CO 2 and H 2 O (see. Karboangidraza ), oxidation of alcohol in a liver (see. Alcohol dehydrogenase ), the proteolytic proteolysis (see. Karboksipeptidaza ). Kaltsiysoderzhashchy enzyme amylase (see) catalyzes splitting of starch in a digestive tract of animals and the person.

Ions of magnesium, calcium, manganese, iron, cobalt, copper, zinc and molybdenum are M.'s part. From 2 to 8 atoms of metal support Nek-rye M., and metals can be different. Except for existence in a molecule of ions of metal and the properties caused by presence of these ions, M. on chemical structure, structure and physical. - to chemical properties do not differ from other proteins (see).

Atoms of copper, molybdenum and zinc are present a metalloprotein, at a molecule to-rogo at the same time, is metallotionein; atoms of copper, cobalt and zinc — enzyme of superoxide dismutase (destroys superoxidic radicals of O 2 - ); atoms of iron, zinc and copper — a tsisteaminoksidaz (catalyzes oxidation of HS — CH 2 CH 2 NH 2 ), atoms of iron and copper — cytochrome oxydase (catalyzes electron transfer in mitochondrions at tissue respiration) and a fenilalaningidroksilaza (see. Phenylalanine ). The lack or surplus of an organism of these metals causes disturbance of synthesis and the corresponding M.' properties, and also another necessary for an organism metalloorganic compounds (see) that leads to disorder of its vital functions. As other cause of infringement of structure and properties M. serve mutational changes in the genetic device that is the reason of a number of hereditary diseases (see. Enzymopathies ).

Bibliography: Lenindzher A. Biochemistry, the lane with English, page 64, M., 1976; X are rice of. Fundamentals of biochemical genetics of the person, the lane with English, M., 1973; Coleman J. E. The reactivities of functional groups of metalloproteins, in book: Biochemistry, ed. by H. Gutfreund, 1 ser., v. 1, p. 185, L. — Baltimore, 1974.

A. M. Shaposhnikov.