SPHINGOLIPIDS — eurysynusic difficult lipids in live organisms, to-rykh are molecular composition sphingosines. Genetically caused disturbance of exchange of S. is the reason of hereditary diseases of accumulation — sphingolipidoses (see). At coronary atherosclerosis in blood note increase in sfingolipidny fraction of phospholipids (see. Phosphatides ), what serves one of additional diagnostic tests at this disease.
Pages divide into two groups. The sfingofosfoligshda containing the rest phosphoric to - you enter into the first group (see. Phosphoric acids). The main representatives of this group C. — sphingomyelins (see) are widely presented in cellular membranes, are found in a blood plasma; it is especially rich with sphingomyelins nervous tissue (see). Also phytosphingolipids (phytoglycolipids) found in plants enter into group of sfingofosfolipid. These lipids making apprx. 5% of total quantity of phospholipids in seeds of plants contain phytosphingosine, fatty acids (see), an inositol (see), phosphoric to - that, and also the remains of geksozamin, hexuronic to - you, galactoses, pectine sugars and mannoses. Sfingoglikolipida concern to the second group C., molecules to-rykh contain the remains of sugars and do not contain phosphate, they can also be carried to to glycolipids (see). The elementary representatives and the most important predecessors of all S. are zhirnokislotny ethers of sphingosine — N-atsilsfingoziny (ceramides). Their monosaccharides containing the rest of hexose are called cerebrosides (see). In a molecule of sulfoethers of cerebrosides — sulfatides (see), or sulfolipids, sulfuric to - that forms an ester group with Z '-ON-grugshoy the rest of a galactose (see). Sulfatproizvodnoye of cerebroside of phrenosin in large numbers meets in white matter of a brain. The special group of sfingoglikolipid is made by tseramidoligosakharida — gangliosides (see), the difficult, carbohydrate-rich S. containing, at least, one rest of N-atsetilneyraminovoy to - you (see. Sialic acids ). Gangliosides — specific components of neurons of gray matter of a brain. Data on the main S.' maintenance in nervous tissue of the person are presented in the table.
Table. The MAINTENANCE of the MAIN SPHINGOLIPIDS IN NERVOUS TISSUE of the PERSON (percentage of total quantity of lipids)
Active synthesis of S. happens in a brain, a liver, kidneys and other bodies. S.'s synthesis in a brain is especially intensive during the period myelinations (see). The general initial stage of synthesis of S. is formation of ceramide in reaction of acylation of sphingosine the rest fat to - you atsil-KOA, catalyzed sfingo-zinatsiltransferazy (KF 2. 3. 1. 24). All other Pages are formed of ceramides. Sphingomyelins are derivatives of ceramide after accession to it cytidinediphosphate (TsDF) - sincaline. At consecutive transfer on ceramide of the remains of glucose, a galactose, N-atsetilgalaktozamina and N-acetyl-neuraminic to - you in reactions about uridinediphosphate (UDF) - proivvodny these sugars gangliosides are formed, and at accession to ceramide of the remains of glucose or a galactose — cerebrosides. Sulphation of cerebrosides with formation of sulfatides is carried out in microsomes in reaction with so-called active sulfate — Z '-phospho-adenosine-5 '-phosphosulphate (FAFS). Also alternative paths of synthesis of S. E.g. are found, sphingosine can react with TsDF-sincaline, and formed sfingozinfosforilkholin — with atsil-KOA, at the same time sphingomyelins are synthesized. Synthesis of cerebrosides can begin reaction of sphingosine with the UDF-galactose with formation of a galaktozilsfingozin (psikhozin), to-ry, reacting with atsil-KOA, forms cerebroside. S.'s catabolism proceeds with the participation of specific lysosomic hydrolases (see): sphingomyelinases, sulphatases (see), alpha galactosidases, (3 galactosidases, geksozaminidaz, etc. In normal conditions of S. constantly are synthesized and catabolize in an organism. In absence or at partial insufficiency of lysosomic hydrolases (most often caused genetically) in fabrics there is an abnormal accumulation of the corresponding S. (see. Lipidoses ).
In a wedge, practice (including for diagnosis of sphingolipidoses) define various S.' maintenance in biol. liquids and tissues of the person. Methods of the analysis of S. are similar to methods of definition of phospholipids and glycolipids.
See also Lipids, biochemical methods of a research .
Bibliography: Zhukova I., and Smirnova G. I. Glycolipids, in book: Usp. biol. chemical, under the editorship of B. A. Stepanenko, t. 9, page 220, M., 1968, bibliogr.; At and y t And., etc. Fundamentals of biochemistry, the lane with English, t. 1 — 3, M., 1981; Michalec C. Biochemistry of sphingolipids, Praha, 1967» bibliogr.; S t o f f e 1 W. Sphingolipids, Ann. Rev. Biochem., v. 40, p. 57, 1971, bibliogr.; Wiegandt H. Glycosphin-golipids, Advanc. Lipid Res., v. 9, p. 249, 1971, bibliogr.
H. V. Gulyaeva.