Xylose
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| Names | |||
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| IUPAC name d-Xylose | |||
| Systematic IUPAC name d-xylo-Pentose[1] | |||
| Other names (+)-Xylose Wood sugar | |||
| Identifiers | |||
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| 3D model (JSmol) | |||
| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.043.072 | ||
| EC Number | 
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| PubChem CID | |||
| UNII | 
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| Properties[2][3] | |||
| C 5H 10O 5 | |||
| Molar mass | 150.13 g/mol | ||
| Appearance | monoclinic needles or prisms, colourless | ||
| Density | 1.525 g/cm3 (20 °C) | ||
| Melting point | 144 to 145 °C (291 to 293 °F; 417 to 418 K) | ||
| Chiral rotation ([α]D) | +22.5° (CHCl 3) | ||
| −84.80·10−6 cm3/mol | |||
| Hazards | |||
| NFPA 704 (fire diamond) | |||
| Related compounds | |||
| Related aldopentoses | Arabinose Ribose Lyxose | ||
| Related compounds | Xylulose | ||
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
Xylose (cf. Ancient Greek: ξύλον, xylon, "wood") is a common monosaccharide, i.e. a simple sugar. Xylose is classified as aldopentose type, which means that it contains five carbon atoms and includes an aldehyde functional group, at least in its open-chain form. It is abundant in biomass, and is one of the most abundant sugars in nature.[4] It is a white, water-soluble solid.
Structure
[edit]The acyclic form of xylose has chemical formula HOCH
2(CH(OH))3CHO.  Cyclic hemiacetal isomers are more prevalent in solution. These cyclic isomers include the pyranoses feature six-membered C5O rings, and the furanoses, which feature five-membered C
4O rings (with a pendant CH
2OH group).  Each of these rings is subject to further isomerism, depending on the relative orientation of the anomeric hydroxy group.
The dextrorotary form, d-xylose, is the one that usually occurs endogenously in living things. A levorotary form, l-xylose, can be synthesized.
Occurrence
[edit]Xylose is the main building block for the hemicellulose xylan, which comprises about 30% of some plants (birch for example), far less in others (spruce and pine have about 9% xylan). Xylose is otherwise pervasive, being found in the embryos of most edible plants. It was first isolated from wood by Finnish scientist, Koch, in 1881,[5] but first became commercially viable, with a price close to sucrose, in 1930.[6]
Xylose is also the first saccharide added to the serine or threonine in the proteoglycan type O-glycosylation, and, so, it is the first saccharide in biosynthetic pathways of most anionic polysaccharides such as heparan sulfate and chondroitin sulfate.[7]
Xylose is also found in some species of Chrysolinina beetles, including Chrysolina coerulans. They have cardiac glycosides (including xylose) in their defensive glands.[8]
Applications
[edit]Chemicals
[edit]The acid-catalysed degradation of hemicellulose gives furfural,[9][10] a precursor to synthetic polymers and to tetrahydrofuran.[11]
Human consumption
[edit]Xylose is not a major human nutrient and is largely excreted by the kidneys.[12] Humans can obtain xylose only from their diet. An oxidoreductase pathway is present in eukaryotic microorganisms. Humans have enzymes called protein xylosyltransferases (XYLT1, XYLT2) which transfer xylose from UDP to a serine in the core protein of proteoglycans.
Xylose contains 2.4 calories per gram[13] (lower than glucose or sucrose, approx. 4 calories per gram).
Animal medicine
[edit]In animal medicine, xylose is used to test for malabsorption by administration in water to the patient after fasting. If xylose is detected in blood and/or urine within the next few hours, it has been absorbed by the intestines.[14]
High xylose intake on the order of approximately 100 g/kg of animal body weight is relatively well tolerated in pigs, and in a similar manner to results from human studies, a portion of the xylose ingested is excreted in urine unmodified.[15]
Derivatives
[edit]Reduction of xylose by catalytic hydrogenation produces the sugar substitute xylitol.
See also
[edit]References
[edit]- ^ "Appendix". iupac.qmul.ac.uk. Retrieved 2025-08-17.
- ^ The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.). Merck. 1989. ISBN 091191028X., 9995.
- ^ Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, Florida: CRC Press. p. C-574. ISBN 0-8493-0462-8..
- ^ Thorsheim, Karin; Siegbahn, Anna; Johnsson, Richard E.; Stålbrand, Henrik; Manner, Sophie; Widmalm, Göran; Ellervik, Ulf (2015). "Chemistry of xylopyranosides". Carbohydrate Research. 418: 65–88. doi:10.1016/j.carres.2015.10.004. PMID 26580709.
- ^ Hudson, C.S.; Cantor, S.M., eds. (2014) [1950]. Advances in Carbohydrate Chemistry. Vol. 5. Elsevier. p. 278. ISBN 9780080562643.
- ^ Miller, Mabel M.; Lewis, Howard B. (1932). "Pentose Metabolism: I. The Rate of Absorption of d-Xylose and the Formation of Glycogen in the Organism of the White Rat after Oral Administration of d-Xylose". Journal of Biological Chemistry. 98 (1): 133–140. doi:10.1016/S0021-9258(18)76145-0.
- ^ Buskas, Therese; Ingale, Sampat; Boons, Geert-Jan (2006), "Glycopeptides as versatile tool for glycobiology", Glycobiology, 16 (8): 113R – 36R, doi:10.1093/glycob/cwj125, PMID 16675547
- ^ Morgan, E. David (2004). "§ 7.3.1 Sterols in Insects". Biosynthesis in Insects. Royal Society of Chemistry. p. 112. ISBN 9780854046911.
- ^ Adams, Roger; Voorhees, V. (1921). "Furfural". Organic Syntheses. 1: 49. doi:10.15227/orgsyn.001.0049; Collected Volumes, vol. 1, p. 280.
- ^ Gómez Millán, Gerardo; Hellsten, Sanna; King, Alistair W.T.; Pokki, Juha-Pekka; Llorca, Jordi; Sixta, Herbert (25 April 2019). "A comparative study of water-immiscible organic solvents in the production of furfural from xylose and birch hydrolysate". Journal of Industrial and Engineering Chemistry. 72: 354–363. doi:10.1016/j.jiec.2018.12.037. hdl:10138/307298. S2CID 104358224.
- ^ Hoydonckx, H. E.; Van Rhijn, W. M.; Van Rhijn, W.; De Vos, D. E.; Jacobs, P. A. (2007). "Furfural and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a12_119.pub2. ISBN 978-3527306732.
- ^ Johnson, S.A. (2007-08-24). Physiological and microbiological studies of nectar xylose metabolism in the Namaqua rock mouse, Aethomys namaquensis (A. Smith, 1834) (PhD). hdl:2263/27501.
- ^ US US6239274B1, "Method of producing xylose", issued 1999-08-06
- ^ "D-xylose absorption", MedlinePlus, U.S. National Library of Medicine, July 2008, retrieved 2009-09-06
- ^ Schutte JB, de Jong J, Polziehn R, Verstegen MW (July 1991). "Nutritional implications of D-xylose in pigs". Br J Nutr. 66 (1): 83–93. doi:10.1079/bjn19910012. PMID 1931909. S2CID 27670020.
 
	





