DNA: a base or an acid?

J.R. Pelmont jp10 at calvanet.calvacom.fr
Wed Oct 16 17:11:53 EST 1996


 
> It is an acid because of the phosphate groups on the sugar-phosphate 
> backbone.  The bases in DNA are weak compared to the negatively charged
> phosphate groups.

Yes of course, and it is a matter of pKa, the value of which is well
under 7 for the phosphate, while the pKa of adenine and other bases is
too high, so they should carry negligible positive charges at neutral
pH.
In chromatin the negative charges of DNA are neutralized by basic
proteins, the histones. Cations, especially divalent cations (Mn, Mg,
...) are important too in the biochemistry of nucleic acids.
           



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