What is Chondroitin sulfate?
[[Image:Chondroitin Sulfate Structure NTP.png|thumb|240px|Chemical structure of one unit in a chondroitin sulfate chain. Chondroitin-4-sulfate: R<sub>1</sub> = H; R<sub>2</sub> = SO<sub>3</sub>H; R<sub>3</sub> = H. Chondroitin-6-sulfate: R<sub>1</sub> = SO<sub>3</sub>H; R<sub>2</sub>, R<sub>3</sub> = H.]] [[Image:Chondroitin sulfate.svg|thumb|240px|Chondroitin sulfate - alternate diagram]] '''Chondroitin sulfate''' is a sulfated [[glycosaminoglycan]] (GAG). It is a chain of alternating [[sugar]]s ([[N-Acetylgalactosamine|N-acetylgalactosamine]] and [[glucuronic acid]]). It is usually found attached to [[protein]]s as part of a [[proteoglycan]]. A chondroitin chain can have over 100 individual sugars, each of which can be sulfated in variable positions and quantities. Chondroitin sulfate is an important structural component of [[cartilage]] and provides much of its resistance to [[compressive stress|compression]].<ref>{{cite journal | author=Baeurle SA, Kiselev MG, Makarova ES, Nogovitsin EA |title=Effect of the counterion behavior on the frictional–compressive properties of chondroitin sulfate solutions| journal=Polymer|year=2009|volume=50 | issue=7|pages=1805–1813| doi=10.1016/j.polymer.2009.01.066}}</ref> Along with [[glucosamine]], chondroitin sulfate has become a widely used [[dietary supplement]] for treatment of [[osteoarthritis]]. It is commonly extracted from [[shark]] cartilage. ==Terminology== Chondroitin sulfate was originally [[wikt:isolated|isolated]] well before chemists learned its structure. So, its name changed over time.<ref>{{cite journal|author = P. A. Levene and F. B. La Forge| title = On Chondroitin Sulphuric Acid |url = https://archive.org/details/sim_journal-of-biological-chemistry_1913_15/page/69|journal = J. Biol. Chem.| year = 1913|volume= 15| pages = 69–79| doi = 10.1016/S0021-9258(18)88542-8 | doi-access = free }} [http://www.jbc.org/cgi/reprint/15/1/69 Free PDF online] {{Webarchive|url=https://web.archive.org/web/20081105201300/http://www.jbc.org/cgi/reprint/15/1/69 |date=2008-11-0