Editing Agarose (section)

== Structure ==
[[File:Agarose polymere.svg|right|thumb|The structure of the repeating unit of an agarose polymer.]]
Agarose is a linear polymer with a molecular weight of about 120,000, consisting of alternating <small>D</small>-[[galactose]] and 3,6-anhydro-<small>L</small>-galactopyranose linked by α-(1→3) and β-(1→4) glycosidic bonds. The 3,6-anhydro-<small>L</small>-galactopyranose is an <small>L</small>-galactose with an anhydro bridge between the 3 and 6 positions, although some <small>L</small>-galactose units in the polymer may not contain the bridge. Some <small>D</small>-galactose and <small>L</small>-galactose units can be [[methylated]], and [[pyruvate]] and [[sulfate]] are also found in small quantities.<ref>{{cite web |url=http://www.fao.org/docrep/x5822e/x5822e03.htm |title= Chapter 1 - Production, Properties and Uses of Agar | vauthors = Armisen R, Galatas F |publisher=Fao.org }}</ref>

Each agarose chain contains ~800 molecules of galactose, and the agarose polymer chains form helical fibers that aggregate into supercoiled structure with a radius of 20-30&nbsp;nanometer (nm).<ref>{{cite book |title=Molecular Cloning - A Laboratory Manual | vauthors = Maniatis T, Fritsch EF, Sambrook J |volume=1 |chapter=Chapter 5, protocol 1 |year=1982 |page=5.4 |isbn=978-0879691363 }}</ref> The fibers are quasi-rigid, and have a wide range of length depending on the agarose concentration.<ref>{{cite book |url=https://books.google.com/books?id=A-AiYsGTd38C&pg=PA226 |title=Food Polysaccharides and Their Applications | veditors = Stephen AM, Phillips GO  |page=226 |publisher=CRC Press |year=2006 |isbn=978-0824759223 }}</ref> When solidified, the fibers form a [[Three-dimensional space|three-dimensional]] mesh of channels of diameter ranging from 50&nbsp;nm to >200&nbsp;nm depending on the concentration of agarose used - higher concentrations yield lower average pore diameters. The 3-D structure is held together with [[hydrogen bond]]s and can therefore be disrupted by heating back to a liquid state.