Agarose

(1 → 4 ) -3,6 -anhydro- α -L- galactopyranosyl- ( 1 → 3) - β -D - galactopyranan

Biopolymer

White to pale yellow odorless solid

Fixed

≈ 0.9 g/cm3

88 ° C.

Slightly soluble in water ( when heated )

Agarose is a polysaccharide of D-galactose and 3,6-anhydro -L- galactose, which are glycosidically linked. It represents the main component of the agar and is obtained mainly from the Rotalgengattungen Gelidium and Gracillaria. In contrast to the purified agar agarose contains much less negative charges. Agarose is a strong gelling agent and is responsible for the gelling ability of the agar.

Agarose is the name of a gel which is used in the agarose gel for the electrophoretic separation of substances, such as nucleic acids or proteins. It is produced by boiling of agarose in a buffer, such as TBE buffer, or TAE buffer in LB buffer. The concentration of agarose in the buffer depends on the size of the fractionated by gel electrophoresis particles, smaller particles for better separation (spatial resolution) can be achieved with a higher percentage scheduled agarose gel for larger with a low percentage gel. For the agarose gel electrophoresis of plasmids and their restriction fragments are used, for example, usually has a concentration of 0.7 to 1.2 % agarose in the gel buffer.

1000-30000

For the separation of RNA specific formaldehyde - containing gels must be used. Often the gels may be added during the preparation excipients for visualizing the separated molecules. In the case of DNA, these are mostly ethidium bromide.

Further applications of agar or agarose refer to techniques of immunodiffusion ( Ouchterlony test or Ouchterlony double immunodiffusion ) or immunoelectrophoresis. Cross-linked agarose, sold under the trade name Sepharose, which is agarose -Pharmacia separation. Sepharose is used as stationary phase for the chromatographic separation of biomolecules. Coated with protein A or protein G sepharose beads ( beads English ) are used in the immunoprecipitation.

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