Serine, an amino acid with a polar side chain bearing a hydroxyl group (-OH), does not possess a hydrophobic side chain. Its hydrophilic nature arises from the ability of its hydroxyl group to participate in hydrogen bonding, acting as both an acceptor and donor. This hydrogen bonding capability plays a significant role in protein structure and function, contributing to secondary structures like alpha-helices and beta-sheets and influencing tertiary and quaternary protein conformations. Serine’s hydroxyl group also facilitates enzyme catalysis, protein-ligand interactions, and protein-protein interactions, highlighting its diverse functionalities within proteins.
