HYALURONIC ACIDS

From Big Medical Encyclopedia

HYALURONIC ACIDS — group of acid glikozaminoglikan (mucopolysaccharides) which molecules are constructed of the remains D-glucuronic to - you and a N-acetyl-in-glycosamine; the most important component of the main substance of connecting fabric, vitreous and synovial fluids. Aminosugar in a molecule G. to. it is connected with D-glucuronic to - that beta (1-4) - communication, and to - that to aminosugar — beta (1 — 3) - communication. Thus, polymer G. forms to.

Pier. the weight (weight) of G. to. fluctuates from 0,086*10^6 до10*10^6 that the pier depends on an origin of drug, a way of allocation and a method of determination of size. weight.

To. are high-molecular polyelectrolytes, rastvorima in water and are insoluble in organic solvents. To. are optically active, [a]D in water for G. to. fluctuates from — 47 ° to — 78 °. In G.'s flow to. the phenomena of double refraction can be found.

In solution G. to. have exclusively high specific hydrodynamic volume — one molecule G. to. holds 200 — 500 water molecules. In water solutions G. to. intermolecular interaction are strongly expressed that is shown in the high size of intrinsic viscosity (within 2,5 — 5,5 Stokes) and accurately expressed dependence of size of viscosity of solution G. to. from concentration of the polymer and ionic strength of solution. To. in water solutions can form system of the closed three-dimensional grid of molecular chains. Such spatial structure shows resistance to passing through it separate macromolecules already at G.'s concentration to. 0,10 - 3 — 1•10 - 3 g/ml. Thus, though G. to. also do not form gels, but in many respects behave as gel and are concerning other macromolecules molecular sieves (see).

To. form salts with inorganic and organic bases and metachromatic complexes with toluidine blue and other dyes, and also connect to various proteins therefore the difficult soleobrazny complexes which are characterized by extremely high viscosity turn out. At some G. to. existence of a small amount (1 — 2%) covalently of the connected low-molecular protein is established. From synovial fluid the natural complex G. is allocated to. with protein about a pier. it is powerful apprx. 10 6 . In acidic environment G. to. with proteins form so-called mutsinovy clots.

Biol, value G. to. is first of all that they are one of the most important components of the main substance of connecting fabric where carry out a role of the cementing agent, «sticking together» separate fabric elements and cells. To. influence permeability of fabrics. Barrier functions of the main intercellular substance considerably are defined by the maintenance of G. in it to. and their physical. - a chemical state. To. owing to high hydrophily connect intersticial water in intercellular spaces therefore counteraction of fabrics to compression sharply increases. G.'s presence to. in synovial fluid causes its high structural viscosity that gives to joints the chance to maintain big loading at small speeds of the movement. The vitreous of an eye consisting generally of G. to., provides a constant of the internal pressure (turgor) of an eye. Penetration of a spermatozoon in an ovum becomes possible only after hydrolytic decomposition of G. to., connecting follicular cells around an ovum.

To. have a direct bearing on transport and distribution of water in fabrics of an animal organism. As G. to. are polyelectrolytes, they together with other acid glikozaminoglikana participate in ion exchange.

G.'s biosynthesis to. it is investigated insufficiently. Studying of biosynthesis of G. to. a hemolitic streptococcus of group A using glyukozy-1- 14 With and glyukozy-6- 14 With showed that the remains of N-atsetilglyukozamina and D-glucuronic to - you, entering a molecule G. to., are formed of glucose without preliminary rupture of a carbon chain of an initial molecule.

Source of an amino group (NH 2 - groups) a glycosamine the glutamine is. Concerning the mechanism of molecule polymerization of G. to. there is no uniform point of view. According to opinion of one researchers, the disaccharide formed with direct participation of uridinetriphosphate is extended with consecutive accession of monosaccharides to it. On other representations, at first it is formed disakhariduridinnukleotid, from to-rogo then polymer is formed.

G.'s exchange to. in an animal organism happens to rather high speed («a half-cycle of life» of G. to. makes apprx. 2 days).

For receiving drugs G. to. most often use umbilical cords and a vitreous of an eye.

Specific methods for analytical definition of G. to. does not exist, In solutions, free of other mucopolysaccharides, they can be determined by the maintenance of a glycosamine, by quantity of the insoluble proteinaceous complex which is formed in acid medium after addition of protein. In the latter case quantitative measurements are taken nefelometrichesk or in the formed complex protein quantitatively is defined. In enzimol. researches G.'s decrease to. it is possible to determine also by decrease in relative viscosity of solution, by reduction of ability to form a mutsinovy clot, and also by quantitative measurement of hydrolysates.

Gistokhim, G.'s identification to. it is based on G.'s hydrolysis to. testicular or pneumococcal hyaluronidase (see) taking into account their substrate specificity. It is considered that processing of fabric cuts the specified enzymes in various combinations and coloring by their metachromatic dyes (e.g., toluidine blue) are sufficient to define existence in fabrics to. or other acid mucopolysaccharides. However presence at some fabrics of the chondroitin which is treated to action hyaluronidases of an animal and bacterial origin deprives this method of specificity. Besides, G. to. at low concentrations do not find the phenomenon of a metachromasia. At last, the crucial role is played by purity of fermental drugs. Availability of impurity of proteolytic enzymes in them can distort results completely. In certain cases G. to. together with other acid mucopolysaccharides can be revealed on ability to connect trivalent iron which then is defined in the form of Prussian blue.

At a row patol, states there is a disturbance of exchange of G. to. The important role belongs to G. to. in the course of mucoid swelling — an early stage of disorganization of connecting fabric at collagenic diseases (see). G.'s accumulation to. and other mucopolysaccharides in sites of defeat involves increase in hydration of fabric, increases vascular and fabric permeability. At a pseudorheumatism in synovial fluid G.'s maintenance to. raises. The same is noted in hypodermic rheumatic small knots, in pleural liquid at mesothelioma of a pleura and in a blood plasma at patients with a reticulosarcoma.

G.'s exchange to. it is regulated by hormones thyroid and gonads, adrenocorticotropic hormone, a cortisone, etc.

G. to. finds rather broad application as medicine and it is applied as biogenic drug (see. Luronit , Vitreous ).

See also Mucopolysaccharides , Polysaccharides .


Bibliography: S. M bull-calves. New data on glikozaminoglikan (mucopolysaccharides), Usp. sovr, biol., t. 65, century 3, page 323, 1968, bibliogr.; B y h to about in S. M. and Kolesnikov M. F. Studying of high cleaning drugs of hyaluronic acid, Biochemistry, t. 34, century 1, page 204, 1969, bibliogr.; Brimacombe J. S. and. W e b b e of J.M. Mucopolysaccharides, p. 43, Amsterdam a. lake of 1964; Laurent T. Page of Structure of hyaluronic acid, in book: Chem. molec, biol, of the intercellular matrix, ed. by E. A. Balazs, v. 2, p. 703, L. — N. Y., 1970; Preston B. N., Davies M. O g s t o n A. G. The composition and physicochemical properties of hyaluronic acids prepared from ox synovial fluid and from a case of mesothelioma, Biochem. J., v. 96, p. 449, 1965.

S. M. Bychkov.

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