Any of a group of polysaccharides with high molecular weight that contain amino sugars and often form complexes with proteins. Also called mucopolysaccharide.
[GLYC(O)- + (HEX)OS(E) + AMIN(E) + glycan, polysaccharide (GLYC(O)- + -AN2).]
glycosaminoglycan
Did you mean: glycosaminoglycan, mucopolysaccharide (in biochemistry)
Dictionary:
gly·cos·a·mi·no·gly·can (glī'kōs-ə-mē'nō-glī'kăn)  |
n.
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| Veterinary Dictionary: glycosaminoglycan |
Any of the carbohydrates containing amino sugars occurring in proteoglycans, e.g. hyaluronic acid or chondroitin sulfate. These substances are secreted in very much greater quantities in the urine of achondroplastic dwarf calves than in other urines. This suggests that the disease is an inherited defect of metabolism similar to the mucopolysaccharidoses of humans. See also glycogenosis.
- g. polysulfate — an antiarthritic compound which affects synovial membrane activity, increasing viscosity of synovial fluid.
| Wikipedia: Glycosaminoglycan |
GAGs and GAGS redirect here, if you were looking for the comedy see Just For Laughs Gags.
If you were looking for the device to prevent speech see Gag or for other uses of the word 'gag' see Gag (disambiguation)
Glycosaminoglycans[1] (GAGs) or mucopolysaccharides[2] are long unbranched polysaccharides consisting of a repeating disaccharide unit.
Contents |
Production
Protein cores made in the rough endoplasmic reticulum are posttranslationally modified by glycosyltransferases in the Golgi apparatus, where GAG disaccharides are added to protein cores to yield proteoglycans; the exception is hyaluronan, which is uniquely synthesized without a protein core and is "spun out" by enzymes at cell surfaces directly into the extracellular space.
Function
This family of carbohydrates is essential or important for life.
GAGs form an important component of connective tissues. GAG chains may be covalently linked to a protein to form proteoglycans. Water sticks to GAGs, this is where the resistance to pressure comes from. The density of sugar molecules and the net negative charges attract salts. Ex: Na+, and after the sodium binds it attracts water molecules. Water does not compress, unlike gas.
Some examples of glycosaminoglycan uses in nature include heparin as an anticoagulant, hyaluronate as a component in the synovial fluid lubricant in body joints, and chondroitins which can be found in connective tissues, cartilage and tendons.
Classification
Members of the glycosaminoglycan family vary in the type of hexosamine, hexose or hexuronic acid unit they contain (e.g. glucuronic acid, iduronic acid, galactose, galactosamine, glucosamine).
They also vary in the geometry of the glycosidic linkage.
Examples of GAGs include:
| Name | Hexuronic acid / Hexose | Hexosamine | Linkage geometry between predominant monomeric units | Unique features |
| Chondroitin sulfate | GlcUA or GlcUA(2S) | GalNAc or GalNAc(4S) or GalNAc(6S) or GalNAc(4S,6S) | -4GlcUAβ1-3GalNAcβ1- | Most prevalent GAG |
| Dermatan sulfate | GlcUA or IdoUA or IdoUA(2S) | GalNAc or GalNAc(4S) or GalNAc(6S) or GalNAc(4S,6S) | -4IdoUAβ1-3GalNAcβ1- | Distinguished from chondroitin sulfate by the presence of iduronic acid, although some hexuronic acid monosaccharides may be glucuronic acid.[3] |
| Keratan sulfate | Gal or Gal(6S) | GlcNAc or GlcNAc(6S) | -3Gal(6S)β1-4GlcNAc(6S)β1- | Keratan sulfate type II may be fucosylated.[4] |
| Heparin | GlcUA or IdoUA(2S) | GlcNAc or GlcNS or GlcNAc(6S) or GlcNS(6S) | -4IdoUA(2S)α1-4GlcNS(6S)α1- | Highest negative charge density of any known biological molecule |
| Heparan sulfate | GlcUA or IdoUA or IdoUA(2S) | GlcNAc or GlcNS or GlcNAc(6S) or GlcNS(6S) | -4GlcUAβ1-4GlcNAcα1- | Highly similar in structure to heparin, however heparan sulfates disaccharide units are organised into distinct sulfated and non-sulfated domains.[5] |
| Hyaluronan | GlcUA | GlcNAc | -4GlcUAβ1-3GlcNAcβ1- | The only GAG that is exclusively non-sulfated |
Abbreviations
- GlcUA = β-D-glucuronic acid
- GlcUA(2S) = 2-O-sulfo-β-D-glucuronic acid
- IdoUA = α-L-iduronic acid
- IdoUA(2S) = 2-O-sulfo-α-L-iduronic acid
- Gal = β-D-galactose
- Gal(6S) = 6-O-sulfo-β-D-galactose
- GalNAc = β-D-N-acetylgalactosamine
- GalNAc(4S) = β-D-N-acetylgalactosamine-4-O-sulfate
- GalNAc(6S) = β-D-N-acetylgalactosamine-6-O-sulfate
- GalNAc(4S,6S) = β-D-N-acetylgalactosamine-4-O, 6-O-sulfate
- GlcNAc = α-D-N-acetylglucosamine
- GlcNS = α-D-N-sulfoglucosamine
- GlcNS(6S) = α-D-N-sulfoglucosamine-6-O-sulfate
References
- ^ glycosaminoglycan at Dorland's Medical Dictionary
- ^ mucopolysaccharide at Dorland's Medical Dictionary
- ^ Trowbridge JM, Gallo RL. (2002). "Dermatan sulfate: new functions from an old glycosaminoglycan". Glycobiology 12 (9): 117R–125R. doi:. PMID 12213784.
- ^ Funderburgh JL. (2000). "Keratan sulfate: structure, biosynthesis, and function". Glycobiology 10 (10): 951–958. doi:. PMID 11030741.
- ^ Gallagher, J.T., Lyon, M. (2000). "Molecular structure of Heparan Sulfate and interactions with growth factors and morphogens". in Iozzo, M, V.. Proteoglycans: structure, biology and molecular interactions. Marcel Dekker Inc. New York, New York. pp. 27–59.
See also
- Mucopolysaccharidosis (lysosomal storage diseases)
- Lipopolysaccharide
External links
- Proteoglycans and Glycosaminoglycans at Lancaster University
- Illustration at scientificpsychic.com
- King M. 2005. Glycosaminoglycans. Indiana University School of Medicine Accessed December 31, 2006.
- MeSH Glycosaminoglycans
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Did you mean: glycosaminoglycan, mucopolysaccharide (in biochemistry)
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 | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more |
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| Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved. Read more |
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