FUKOZA

From Big Medical Encyclopedia

FUKOZA (synonym: rhodeose, galaktome-tylose. - dezoksi - L - ra lactose) — methyl pentose, a monosaccharide from group dezoksigeksoz, is a part of uglevodsoderzhashchy connections of animal, plant and bacterial cells. The most widespread L-isomer F. (see the Isomerism) in a stand-at-ease it is found in small amounts in a blood plasma and urine of the person; usually L-fukoza is a component of oligosaccharides (see) or a component of a carbohydrate part of glycoproteins (see), glycolipids (see) and glikozaminoglikan (see Mucopolysaccharides), playing an important role in performance by these connections of their specific functions,


such, e.g., as biol. recognition, etc. Genetically caused insufficiency of a - L - fukozidazy (KF 3.2.1.51), catalyzing eliminating F. from the connections supporting her, is the reason of a serious hereditary illness — a fukozidoza. D-Fukoza is found only in nek-ry bacteria and plants.

Pier. weight (weight) F. makes 164,2; IT is group at the 6th carbon atom in a molecule of this dezoksi-hexose (see Hexoses) it is replaced on hydrogen atom.

L-and D-forms F. form open aldehydic and several cyclic tautomeric forms; g°pl L - fuko-zy 145 °, specific rotation of the plane of the polarized light [a]D = — 153 °.

Chemical properties F. are similar to properties of other monosaccharides (see). It is well a rastvorima in water and it is practically not ether-soluble also other organic solvents. Unlike usual hexoses F. at boiling with strong mineral to-tami (salt or sulfuric) forms 5 methylfurfural (see Trucks trucks of an ola) what quantitative reaction of definition F is based on. and other methyl pentoses in the presence of hexoses (see Dishe methods). The reaction characteristic for F., as well as for other deoxysugars, education at oxidation F is. iodic to - that the acetic aldehyde (see Acetaldehyde) which is not formed at oxidation of usual monosaccharides. It is also the cornerstone of a specific method of quantitative definition F. and other methyl pentoses in the presence of different sugars, in particular hexoses, to-rye at oxidation iodic to - that form formaldehyde (see. Ant aldehyde).

Existence in a molecule F. methyl group causes its high mobility at a chromatography (see) on paper, and also lability of a glycosidic linkage in various fukozosoderzhashchy connections. In the majority of fukozosoderzhashchy connections F. it is connected with other monosaccharides of carbohydrate chains an a-glycosidic linkage. In a human body and animals only two connections, in molecules to-rykh F are known. it is connected to other carbohydrates not and - and a glycosidic linkage. It is the Russian Federation at to about z about - L - fos veils and



guanozindifosfat-r-fukoza, being the universal donor of the fukozilny remains at biosynthesis of fukozosoderzhashchy connections, in Krom high-specific fukoziltransferaza participate.

Receive F. hydrolysis of natural substances, e.g. L-fukozu receive by hydrolysis of fukozosoder-zhashchy polysaccharide of seaweed of a fukan.

The richest source containing L-fukozu of oligosaccharides is women's milk. Occur among oligosaccharides of women's milk mono - di - and trifukozil-derivatives. In urine of the person L are found - a fukozil-myo-inositol, 2-O-a-L-fukozil - D-glucose and nek-ry another containing F. oligosaccharides.

L-fukoza is a part of a number of serumal immunoglobulins (see), transport glycoproteins (see), such as ceruloplasmin and lactoferrin. It is found as a part of the nek-ry lysosomic hydrolases (see) having the glikoproteidny nature; in P-D-glucuronidase (see Glucuronidases), glucoamylase (see. And milaza), P-N-atsetilgeksozaminida-ze, and also as a part of a - L - fukozida-zy, allocated from various bodies of animals and the person. L-fukoza is found in a chorionic gonadotrophin (see) and follicle-stimulating hormone (see). Carbohydrate chains of group-specific substances (see) blood and group-specific substances of the glycolipidic nature also contain L-fukozu in the structure. Quantity F., defining antigenic specificity of N-antigen, in group-specific substances of the ABO(H) system, makes 16 — 22%, in substances of the Lewis system (F. defines serological specificity of Lea antigens ~ and Leb) — 8 — 13% while in other glycoproteins its contents does not exceed 0,2 — 1,5%. T. in oligosakharidny chains of glycoproteins holds usually trailer position along with N-atsetilney-raminovoy to - that (see. Sialic acids). Between quantity F. and to l iches t in m of N - and tset of l neyramino howl to - you in these connections exist inversely proportional dependence.

L-Fukoza was found as a part of glycolipids of plasma membranes (see Membranes biological), it is a component of a number of gangliosides (see) and neutral glycolipids of a brain of the person. Unique glycolipid — a - L - fukopi-ranoziltseramid, containing in quality of a carbohydrate component only F., it was allocated from a carcinoma of a large intestine. In glikozaminoglika-na of L-fukoza meets only as a minor component bo-


new chains along with D-mannose and D-xylose. Presence at carbohydrate chains F. it is characteristic of a kera-tansulfat.

Trailer situation F. in oligo-sakharidny chains causes, apparently, a special role of this sugar in biol. recognition and in some other the major processes of a live organism. The important role F is established. as peculiar marker of the transport glycoprotein which is specifically recognized by receptors on membranes of hepatocytes. Believe that the remains F. on the surfaces of lymphocytes (see) oriented outside participate in recognition of lymphocytes other cells of an adenoid tissue (see. Immunocompetent cells). Removal F. from a surface of lymphocytes before their introduction to a blood stream leads to the fact that these lymphocytes appear not in a spleen, as usual, and in a liver.

It is shown that F. plays an essential role in the course of removal of a glyukotserebrozidaza from a blood-groove and absorption of this enzyme hepatocytes. After processing of a glyukotserebrozidaza of a - L - fukozidazoy (i.e. eliminating of the rest F. from a molecule of fermental protein) it was absorbed by hepatocytes in much smaller degree, than native enzyme. On a surface of macrophages (see) there are specific receptors which are «learning» the remains F. glyconew part of molecules of elastase and cathepsine of D of leukocytes of the person.

There are data that the rest F. specific receptors of the glikoproteidny nature on a surface of macrophages otvetstven for linkng with a macrophage of MIF — the factor (English migration inhibitory factor) inhibiting migration of macrophages (see Mediators of cellular immunity). It is revealed also that F. and sialine to - that glycoproteins — receptors of a surface of macrophages provide interaction with these cells not only MIF, but also MAF of the factor causing aggregation of macrophages (English macrophage aggregation factor).

In animal fabrics the activated form F. — GDF (guanozindi-phosphate) of a fukoz can be formed of glucose by difficult enzymatic transformations: a glitch

for —> glyukozo-6-phosphate fruktozo-

6 phosphate —> mannozo-6-phosphate — ► mannozo-1-phosphate —> Gdfmannoza —> Gdffukoza. Education of the main donor of the remains F. at biosynthesis of carbohydrate chains of glycoconjugates — Ffukoza's State Duma can occur also at direct phosphorylation (see) T. in the following reactions: a fukoza + ATP — >fukozo-1-phosphate + ADF; fukozo-1-phosphate + GTF (guanozintrifosfat) — ► Gdffukoza. Inclusion of the remains F. in molecules of various oligosaccharides, glycoproteins and glycolipids it is catalyzed in the presence of Gdffukoza by the fukoziltransferaza specific to features of structure of acceptor molecules.

Eliminating F. from the connections supporting her it is carried out by means of lysosomic enzyme a - L - fukozidazy, to-ry has the multiple forms (see Isoenzymes). In a human body of a fukozidaz is present practically at all fabrics and biol. liquids. Along with other glikozidaza this enzyme is already found in the person at early stages of an embryogenesis in various bodies of a fruit and in a fetal part of a placenta.

Genetically caused insufficiency of a - L - fukozidazy leads to development of the serious neurovisceral illness fukozido-for relating to hereditary glikozidoza (see Glikozidoza, t. 10, additional materials) and inherited on autosomal recessively type.

Clinical manifestations of a fuko-zidoz are characterized by disturbances from a nervous system: weak-mindedness, sharp decrease in a muscle tone, spasms. At patients increase in a liver, spleen, heart is observed. The increased perspiration is followed by considerable allocation of ions of sodium and chlorine. Disturbances from bones are noted, including deformation of a backbone and change of bones of a craniofacial skeleton.

Clinically allocate two fukozidoz options. At a fukozi-dose of the I type the disease is shown in several months after the birth of the child. The disease quickly progresses, is followed frequent inf. also comes to an end with respiratory diseases with the death of children at the age of 4 — 5 years. At a fuko-zidoza of the II type with atipichesky, less heavy, than at a fukozidoza of the I type, a wedge, a picture patients live up to 14 — 20 years. Fukozidoz II of type is often combined with the diffusion angiokeratoma (see) considered as a distinguishing character of a fukozidoz of this type. At the same time plentiful sweating with the increased ion concentration of sodium and chlorine in sweat (that is typical for heavier fukozidoz of the I type) is usually not observed.

Distinctions in a wedge, a picture at a fukozidoza give the grounds to assume existence of wide genetic heterogeneity of this disease. Genetic defect faugh-kozidazy leads to accumulation in various bodies and tissues of patients fukozidozy the most various products by the nature — fuko-zosoderzhashchy glikozakhminoglika-is new, glycolipids, oligosaccharides.

Of blood serum of the patient» fukozidozy accumulation E-antigenov, the wasps-1,2 supporting two faugh-kozilnykh the rest, connected respectively — and and - 1,4 - communication with the remains of a galactose and a N-acetyl-glycosamine is characteristic. At the same time concentration E-antigenov, in to-rykh one rest F. it is attached and - 1,4 - communication, does not change. It allows to assume that the patient has no fukozidaz of that type, to-ry otvetstven for splitting and - 1,2 - bonds.

In the cultivated fibroblasts of skin of patients fukozidozy note the increased maintenance of a low-molecular glikopeptid like a fukoz — a-1,6-] \G-atsetilglyukoza-min-asparagin, to-ry century this case a key product of accumulation is. In urine of patients fukozidozy a large amount of various fukozosoderzha-shchy oligosaccharides, a part is found to-rykh; it is connected with asparagine.

Biochemical diagnosis of a fukozidoz is carried out by definition of activity of a - L - fukozidazy, edges in various degree decreases in plasma * and blood serum, leukocytes, urine, a liver, kidneys and other fabrics. In the diagnostic purposes usually investigate plasma and blood serum, leukocytes, fibroblasts of skin I wet patients. Prenatal diagnosis of a fukozidoz is based on definition of activity of a fukozidaza of century to culture of cells of an amniotic fluid. Existence of quite high activity of a fukozidaza in a fetal part of a placenta suggests that prenatal diagnosis of a fukozidoz can be based on definition of fukozidazny activity in the material received at a biopsy of a placenta.

Treatment of a fukozidoz is not developed yet. As for development, approaches of enzymotherapy for correction of this disease, they are at a stage of experimental development on culture of cells. Data that fibroblasts of skin of patients fukozidozy are obtained: are capable to absorb from culture medium the cleared a - L - fukozi-Dazu placentae of the person, edges gets into lysosomes and effectively splits the saved-up fukozoso-holding connections there. Forecast of a fukozidoz adverse.

Increase in quantity F. in glycoproteins of blood serum it is noted at aktivnokhm tuberculosis, under-ostrokhm a bacterial endocarditis, cirrhosis and cancer of a liver. However change of quantity F. in these cases is not specific. A nek-ry wedge, researches deserve attention, as a result to-rykh it was succeeded to show accurate and dostovernospetsifichesky changes of contents F. in glycoproteins and glycolipids at nek-ry diseases, napr, at a peptic ulcer and hron. pneumonia. At processes of a malignancy in some cases emergence in fabrics of the specific fukolipid which are absent, as a rule, in intact fabric is revealed.

FUCHSINOPHIL DEGENERATION 449


Bibliography: Beyer E. M and In and d e r-shayn G. Ya. Fukozidaza of the person and animals, Usp. biol. chemistry, t. 23, page 102, 1982, bibliogr.; Vidershayn G. Ya. Biochemical bases of glikozidoz, page 222, 228, M., 1980; Lysosomes and lysosomic diseases of accumulation, under the editorship of J. V. Callahan and J. A. Louden, lane with English, page 318, M., 1984;

The carbo hydrates, chemistry and biochemistry, ed. by W. Pigman a. D. Horton, v. IB, N. Y. — L., 1980; Genetic errors of glycoprotein metabolism, ed. by P. Durand a. J. O’Brien, V. a. o., 1982;

Kenne dy J. F. a. White G. A. Bioactive carbohydrates, in chemistry, biochemistry and biology, N. Y. a. o., 1983.

G. Ya. Vidershayn.

Яндекс.Метрика