Which group of amino acids is most likely to interact with DNA's negatively-charged phosphate backbone?

The interaction between amino acids and DNA is influenced by the chemical properties of the amino acids involved. DNA has a negatively charged phosphate backbone due to the phosphate groups in its structure, which creates an environment that can attract positively charged or polar side chains of certain amino acids.

Polar basic amino acids, such as lysine and arginine, possess positively charged side chains at physiological pH. These positive charges can interact favorably with the negatively charged phosphate groups of DNA, stabilizing the binding of proteins to DNA. This characteristic is essential in many biological processes, including protein-DNA interactions that regulate gene expression.

In contrast, nonpolar amino acids do not have the necessary charge to interact with the phosphate backbone. Similarly, aromatic amino acids generally have neutral or weakly polar properties and do not possess the strong positive charge needed for such interactions. Aliphatic amino acids also lack the necessary polar or charged characteristics, making them less likely to interact meaningfully with the negatively charged regions of DNA.

Therefore, the group of amino acids that is most likely to interact with DNA's negatively charged phosphate backbone is indeed the polar basic amino acids, as their positive charges can effectively form ionic interactions with the negatively charged phosphate groups.