Amino Acids and Hydrogen Bonding

Consider a protein structure that is primarily composed of amino acids. Amino acids contain an amino group, a carboxyl group, and a side chain (R-group) that characterizes each amino acid. The physical and chemical properties of the R-group are crucial for determining the protein's structure and function. In the context of enzymatic activity, the active site of an enzyme is often composed of residues from the R-groups of specific amino acids.

Which of the following amino acids is most likely to participate in hydrogen bonding due to its side chain characteristics?