acidity of DNA

[Postictal Raiden]

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Could someone explain to me why DNA is acidic?

I know that the phosphate group is responsible for its acidity, but why?

In my reasoning, the phosphate group is negatively charged, so it's an electron rich. Being able to donate electron pairs makes should make it a lewis base. In addition, phosphate has the ability to accept two protons. Why is it an acid?

 

[ChemTutor]

Could someone explain to me why DNA is acidic?

I know that the phosphate group is responsible for its acidity, but why?

In my reasoning, the phosphate group is negatively charged, so it's an electron rich. Being able to donate electron pairs makes should make it a lewis base. In addition, phosphate has the ability to accept two protons. Why is it an acid?

DNA is a derivative of phosphoric acid (one OH remains). this makes it a acid.

if we put DNA in water it will behave like an acid: anion and H+
it is negatively charged at physiological pH.