RESPIRATORY PIGMENTS

From Big Medical Encyclopedia

RESPIRATORY PIGMENTS (Latin pigmentum paint) — the painted organic matters of various chemical constitution capable depending on conditions to connect or release molecular oxygen. In a human body and animal Dative carry out transport of oxygen from a respiratory organs to fabrics and take part in processes of biological oxidation and in oxidation-reduction processes. Of Dative respiratory proteins are main and respiratory enzymes (see).

Use of the oxygen dissolved in water one-celled or lowest metazoans is carried out by the organisms living in an aqueous medium as a result of its diffusion through cellular membranes. At more difficult organized animals providing an organism with oxygen happens to the help of the special respiratory proteins transferring oxygen from a respiratory organs to fabrics. Treat such squirrels hemoglobin (see), eritrokruorin, hlorokruorin, hemerythrin, hemocyanin, gelikorubin. Mioglobin (see) it is not capable to transfer oxygen, but participates in its deposition.

Dative is represented by complex proteins — chromoproteids (see) which molecules consist of simple protein and the nonprotein painted prosthetic group.

At many Dative prosthetic group is the zhelezoporfirinovy complex — gems. At vertebrata gemsoderzhashchy respiratory pigments are the hemoglobin which is in erythrocytes and carrying out binding, transport and release of oxygen in fabrics and a myoglobin, with the help to-rogo in muscles oxygen in the quantities sufficient for implementation of the mechanical work performed by muscles is reserved. In intracellular deposition of oxygen, except a myoglobin, apparently, take part being in cells carotinoids (see), and the role of these pigments raises in the conditions of a hypoxia and during the aging of an organism.

More numerous and various are Dative of backboneless animals. High-molecular gemoglobinopodobny substances (pier. weight 400 000 — 6 700 000), dissolved in a hemolymph of annlides (polikht and oligokht) and mollusks, received the name of eritrokruorin. They represent gemsoderzhashchy proteins which part from 30 to 400 groups gem are. Everyone gems is capable to connect one molecule of oxygen. The molecule of an eritrokruorin consists of 12 subunits.

Much in common with eritrokruoriny has hlorokruorin — verditer green of mnogoshchetinkovy annlides (Spirographis and related to them types). It contains in the dissolved state in a blood plasma.

Hlorokruorin — gemsoderzhashchy protein, gems to-rogo differs from gem of hemoglobin in existence of formylation group at the second carbon atom of a protoporphyrinic ring; it carries the name of a spirografisporfirin or spirografisgemin. Pier. the weight of a hlorokruorin fluctuates from 2 750 000 to 3 500 000, the content of iron in it is in limits of 0,45 — 1,2%, the molecule consists of 12 subunits and contains 190 groups of a hlorokruorogem. Hlorokruorin has high affinity to oxygen and insignificant — to carbon monoxide; oxygen capacity of blood of annlides makes 10%.

Hemerythrin — brown-red Dative about a pier. weighing 66 000, is in the cells circulating in band liquid of some species of invertebrates (sea annlides, hl. obr. Sipunculidae, etc.). Hemerythrin differs from other respiratory proteins in what gem does not contain. The molecule of hemerythrin consists of 8 subunits, is in each of which on 2 atoms of iron which, most likely, connect to sulfur atoms, being a part of protein. Content of iron fluctuates from 0,8 to 1,01%, oxygen capacity makes apprx. 1,6%. Property of hemerythrin is reversible to connect to oxygen (each 2 atoms of iron connect one molecule of oxygen) is caused by a special arrangement of polypeptide chains in its molecule.

To Dative carry also gemsoderzhashchy red pigment of a grape snail — gelikorubin, capable to reversible redox.

The respiratory pigments containing copper in the molecule are called hemocyanins. They contain in a blood plasma of many mollusks and arthropods, giving it blue coloring. Hemocyanins represent high-molecular proteins (a pier. weight fluctuates from 500 000 to 10 000 000), the copper content in them makes 0,17 — 0,18% (mollusks) and 0,24 — 0,26% (arthropods). Molecules of hemocyanins have the identical form and consist of 3 — 6 subunits containing a significant amount of atoms of copper (at hemocyanin of their lobster 20) which are located with couples. Hemocyanins differ one from another on the solubility, color (from purple-blue to green) and a form of crystals. They are capable to unite reversibly to oxygen, and one molecule of oxygen contacts two atoms of monovalent copper which at the same time are oxidized. Oxygen capacity of blood of such mollusks and arthropods is proportional to the content in it of copper and quantitatively less, than the oxygen capacity of blood of vertebrate animals. In blood, tissue of a liver and other tissues of animals the cupriferous squirrels who are not participating in transfer of oxygen are found. Treat such squirrels which are Dative hemocuprein and gepatokuprein. They represent verditers blue of identical structure therefore this Dative received the general name of a tsitokupreina. Tsitokuprein — is a protein about a pier. weighing 32 000; the molecule of a tsitokuprein consists of two subunits, each of which contains one atom of copper and one atom of zinc in a bivalent state. It is established that the enzyme of superoxide dismutase catalyzing reaction of dismutation of superoxidic radicals of H2O-collecting in fabrics during oxidizing processes represents tsitokuprein.

As superoxidic radicals and some products of their transformation are extremely toxic, the superoxide scavenger is vital enzyme.

Other cupriferous protein — ceruloplasmin (see. Blood ) — plays a major role in reservation and transport of copper at vertebrate animals and the person. Ceruloplasmin is not only a nontoxic reserve of copper in an organism, but also is also capable to accelerate oxidation of bivalent ions of iron in trivalent, i.e. has ferroksidazny properties, participates in synthesis of hemoglobin and transferrin (iron-binding protein of a blood plasma; normal contents it at the person — 250 mg of %, at defeat of a parenchyma of a liver this figure decreases).

Ceruloplasmin is cupriferous alfa1-globulin of blood serum of the person about a pier. weighing 151 000; about 0,5% of total quantity of protein in a blood plasma of the person and 90% of all copper of a blood plasma fall to his share. At the healthy person the general copper content in a blood plasma makes 70 — 140 mkg of %. Giperkupremiya and a gi-pertseruloplazminemiya are observed in the acute period of the infections proceeding with fever and disintegration of cellular elements at diseases of a liver — hepatitises, cirrhoses and mechanical jaundices, at a carcinoma, leukemia, anemias. The hyper ceruloplasminemia is noted also at pregnancy.

In blood serum quantitative definition of ceruloplasmin is carried out to a wedge, laboratories across Ravin. The method is based on that. that ceruloplasmin is the only component of blood serum having oksidazny properties therefore it catalyzes oxidation of some amines including a parafenilendiamindigidrokhlorida, as a result of oxidation to-rogo substance of blue-violet color is formed. Optical density (see. Colorimetry ) solution it is measured at 530 nanometers, and the concentration of ceruloplasmin proportional to oxidation level of the used substrate, is calculated according to a standard curve. Knowing amount of copper in a blood plasma, it is possible to calculate the content of ceruloplasmin by a formula also:

ceruloplasmin (mg of %) = Cu (mkg of %) • 100/0,32

since theoretically a copper content in ceruloplasmin makes 0,32%.

Also extensive group of the flavonovy pigments painted in yellow or yellowy-brown color and containing a kernel of flavone in the molecule treats Dative (see. Flavones ). These pigments contain in the basic in plants. For animals and the person special value derivatives of flavone, relatives on the chemical structure and biol have, activities and being components of kapillyaroukreplyayushchy citrin. Hesperidin, Rutinum, catechin, epikatekhin and their gallic ethers belong to such Dative. Vitamin P in zooblasts participates in oxidation-reduction processes together with ascorbic to - that, and also is inhibitor of a number of enzymes, especially hyaluronidases (see). Rutinum is capable in certain conditions to stimulate processes of tissue respiration and oxidizing phosphorylation in mitochondrions and, apparently, participates in biosynthesis of an ubikhinon. It is possible that catechin, Rutinum and hesperidin possess adrenalinopodobny action.


Bibliography: Verbolovich P. A. and Uteshev of A. B. Zhelezo in an animal organism, Alma-Ata, 1967, bibliogr.; Karnaukhov V. N. Functions of carotinoids in zooblasts, M., 1973, bibliogr.; Molecules and cells, the lane with English, under the editorship of G. M. Frank, century 4, page 136, M., 1969; F of i-d about at i e h I. Superoxide dismutases, Ann. Rev. Biochem., v. 44, p. 147, 1975, bibliogr.; To lot z J.M., Langerman N. R. a. D and of n a 1 1 D. W. Quaternary structure of proteins, ibid., v. 39, p. 25, 1970, bibliogr.; MalmstromB. G. a. N e i 1 a n d s J. B. Metalloproteins, ibid., v. 33, p. 331, 1964, bibliogr.; Mellema J. E.a. KlugA. Quaternary structure of gastropod haemocyanin, Nature (Lond.), v. 239, p. 146, 1972.

P. A. Verbolovich.

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