Sephadex is a
cross-link
In chemistry and biology, a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural ...
ed
dextran
Dextran is a complex branched glucan (polysaccharide derived from the condensation of glucose), originally derived from wine. IUPAC defines dextrans as "Branched poly-α-d-glucosides of microbial origin having glycosidic bonds predominantly C-1 ...
gel used for
gel filtration. It was launched by
Pharmacia
Pharmacia was a pharmaceutical and biotechnological company in Sweden that merged with the American pharmaceutical company Upjohn in 1995.
History
Pharmacia company was founded in 1911 in Stockholm, Sweden by pharmacist Gustav Felix Grönfel ...
in 1959, after development work by
Jerker Porath and
Per Flodin. The name is derived from separation Pharmacia dextran. It is normally manufactured in a bead form and most commonly used for
gel filtration columns. By varying the degree of cross-linking, the fractionation properties of the gel can be altered.
These highly specialized gel filtration and
chromatographic media are composed of macroscopic beads synthetically derived from the polysaccharide dextran. The organic chains are cross-linked to give a three-dimensional network having functional ionic groups attached by ether linkages to glucose units of the polysaccharide chains.
Available forms include anion and cation exchangers, as well as gel filtration resins, with varying degrees of porosity; bead sizes fall in discrete ranges between 20 and 300
μm.
Sephadex is also used for ion-exchange chromatography.
Sephadex is crosslinked with
epichlorohydrin.
Applications
Sephadex is used to separate molecules by molecular weight. Sephadex is a faster alternative to dialysis (de-salting), requiring a low dilution factor (as little as 1.4:1), with high activity recoveries. Sephadex is also used for buffer exchange and the removal of small molecules during the preparation of large biomolecules, such as ampholytes, detergents, radioactive or fluorescent labels, and phenol (during DNA purification).
A special hydroxypropylated form of Sephadex resin, named Sephadex LH-20, is used for the separation and purification of small organic molecules such as steroids, terpenoids, lipids. An example of use is the purification of cholesterol.
Fractionation
Exclusion chromatography.
Fractionation Range of Globular Proteins and Dextrans (Da).
Ion-exchange chromatography.
Sephadex ion exchangers are produced by introducing functional groups onto the cross-linked dextran matrix. These groups are attached to glucose units in the matrix by stable ether linkages.
See also
*
PEGylation
*
Size exclusion chromatography
*
Superose
*
Sepharose
References
{{Reflist
Biochemistry methods
Chromatography
Swedish brands