Certain proteins associate tightly with DNA by forming ionic

Certain proteins associate tightly with DNA by forming ionic bonds with the

DNA backbone.

(a) Which amino acids have side chains that could form these ionic bonds

with DNA? Give a reason for your answer.

(b) Assuming that the DNA-binding proteins

contain an abundance of the amino acid residues mentioned in your answer to part a, how

would the proteins behave during electrophoresis (in which direction would they move)?

Explain your answer.

Solution

A. Basic amino acids are generally are the ones which form ionic bond with acidic phosphate sugar backbone of DNA. And because they are charged oppositely they form ionic interaction. The example includes histidine, arginine and lysine.

B. As these basic amino acid are positively charged so when subjected to electrophoresis they move towards negatively charged electrode.