Carbohydrate against DNA

Mark Hicks - Genetics Group/University of Alberta mhicks at gpu.srv.ualberta.ca
Tue Nov 22 21:02:46 EST 1994


Thomas said;
>
>Hi
>
>I like to purify DNA out of chicken egg yolk. I always end up with a
>stuff that looks and behaves similar to DNA but is not DNA. I think it is
>a carbohydrate. I wonder if somebody could give me an idea how to remove
>this substance. 
>Now more exactly: I dilute the yolk and make an over night Protein
>degradation with proteinase K. Then I perform a Phenol/Chloroform
>extraction. After the precipitation with isopropanol I get this white
>huge pellet which is not DNA. This Substance cannot be removed with
>Phenol, not digested with amylase or with hyaluronidase. It is water
>soluble (better soluble in acidic solution), makes a kind of gel in basic
>solution. And makes me nervous. What is it? How to remove it. I would be
>grateful for any help
>
>Thanks
>Thomas Hiesberger
>Institute for molecular genetics
>University Vienna


Hi Thomas

	Unfortunately I do not work with chickens but instead I work with trees
.......anyway when I extract DNA from conifers many times starch and carbohydrates
 are associated with the DNA.  The best way to remove them I find is to perform a spermine ppte.
The proceedure that I use is based on a method published in Nucleic Acids Research
volume #9(20)(1981) by Barbara Hoopes et al. pages 5493-5504 called "Studies on the Selectivity
of DNA preciptitation by Spermine".  After the isopropanol ppte. resuspend your DNA in a suitable
volume of TE and then follow the directions in the paper. I have also used another method to remove
unwanted junk from my DNA; a method called differential salt ppte.  Basically you ppte. your
DNA in high salt conc. followed by a second ppte in lower salt conc.  However this method never
seemed to work for me. Getting back to the spermine ppte. other people doing work in flies say 
that a spremine ppte.is the best way to remove any kind of junk from DNA regardless of organism.
Anyway feel free to e-mail me if you have any questions about this stuff.

Cheers,

Mark Hicks
Dept. of Genetics
University of Alberta
Edmonton, Alberta
CANADA
e-mail:  mhicks at gpu.srv.ualberta.ca

 



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