XYLOSE

From Big Medical Encyclopedia

XYLOSE (wood sugar) — the monosaccharide relating to group of pentoses; With 5 H 10 O 5  ; it is found in urine at a pentosuria. At introduction to the person of per os the most part To. it is allocated with urine.

To. exists in the form of D-and L-iso-merov, natural is D - iso - died (see. Isomerism ).

In a human body and animals D-isomer K. is a part of glikozaminoglikan of connecting fabric. D-xylose is found as a part of polysaccharides of wood (in particular, in a xylan of wood), in various glycosides and oligosaccharides.

As well as others monosaccharides (see), To. the rastvorima in water, is insoluble in ether and the majority of organic solvents. It gives all general reactions to aldoses (recovers solution of Felinga, ammoniac AgNO3 solution, forms various osazones) and the staining reactions characteristic for pentoses (see). At action on To. diluted to - the t is formed furfural that is used for quantitative definition To.

Introduction of large numbers To. an experimental animal (young rats) leads to development of a cataract in them.

There are data that disturbance of exchange To. can be the reason of a hereditary disease. In 1970 Peyling-Wright (Page R. Payling-Wright) and P. R. Evans was described a case of inborn insufficiency of the enzyme which hydrolytic is chipping off To. — beta ksilozidazy (KF 3. 2.1.37). At the age of 9 months the sick girl was sluggish, its choreoathetoid movements were observed, the patient lost sight and hearing. In culture of its lymphocytes very low activity beta ksilozidazy is established.



Bibliography: Stepanenko B. N. Carbohydrates, Progress in studying of a structure and metabolism, page 28, etc., M., 1968; The carbohydrates, ed. by W. Pigman, p. 85, N. Y., 1957.


G. Ya. Vidershayn.

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