Hi Nataraja

CTAB complexes DNA and RNA in your samples and precipitates them, otherwise this "impurities" from your fermentation process would persist in your purification process and would make it impossible for you to seperate them from polymeric polysaccharides.

Usually you use CTAB to precipitat an purify DNA or RNA and Plasmid Preps from "impurities" like Polysaccharids

Hello,

CTAB) s a amine based cationic quaternary surfactant. It interact with anionic polysaccharide (ionic interaction) and then decreases their solubility. So after their precipitation, it is possible to collect polysaccharides by filtration or centrifugation. To polish the purification after the collect of pprecipitated polysaccharides it is better to wash them with alcohol or acetone befor drying.

regards

CTAB, as Philippe stated, complexes with anionic polymers, including anionic polysaccharides, RNA and DNA. The complex is relatively insoluble in water. To further process, the precipitated and washed complex can be redissolved in concentrated KCl or NaCl solutions and dialyzed or otherwise cleaned up.

CTAB complexes with polyanionic polymers and since they are less soluble, they precipitate. The precipitate can be recovered by centrifugation, dissolved in 0,1 M NaCl and then precipitated with 6 volumes of ethanol, it helps to remove excess CTAB.

The procedure is also useful to remove polyanionic polymers from a mixture when the neutral polymers are of interest.

I used the CTAB precipitation during my thesis to remove polyanionic polysaccharides from a bacterial crude extract from Enterobacter agglomerans and thus allow the purification of a lipopolysaccharide of interest in the supernatant. The corresponding paper is available in ResearchGate ( https://www.researchgate.net/publication/21762027_Structure_of_the_O-specific_polysaccharide_chain_of_the_lipopolysaccharide_of_Enterobacter_agglomerans ).

A reference for CTAB precipitation is: Scott JE 1965 Methods in Carbohydrate Chemistry Vol. 5, pages 38-44

Article Structure of the O-specific polysaccharide chain of the lipo...

comments are very useful. 

I have one basic Question, Please explain me the use of CTAB in plant DNA extract .