How do hydrogen bonds between amino acid side chains help stabilize proteins?

Hydrogen bonds are essential for stabilizing the three-dimensional structure of proteins. While hydrogen bonding is most famously associated with the peptide link (the backbone of the polypeptide chain) to form secondary structures like the $\alpha$ helix and $\beta$-pleated sheet, these interactions also occur between the side chains (R groups) of amino acids.12

In the context of tertiary structure, the interaction between various side chains helps define the protein's final shape. Hydrogen bonds form when a hydrogen atom, covalently bonded to an electronegative atom like nitrogen or oxygen, is attracted to the lone pair of electrons on another electronegative atom. Within a protein, these bonds facilitate the mutual attraction of adjacent peptide chains.12

Although an individual hydrogen bond is significantly weaker than a covalent bond, the cumulative effect of numerous hydrogen bonds provides substantial stability to the protein's conformation, which is critical for its biological function.12