Examples of hydrogen bond interactions from conserved, buried residues to mainchain atoms in β-hairpins. Representative structures were chosen for each family based on resolution; residues are coloured by atom type with buried, conserved polar residues shown in magenta. Hydrogen bonds are shown in black. Examples of polar sidechains interacting distantly to form hydrogen bonds with mainchain amide groups in β-hairpins including, A) an aspartate in the ribulose bisphosphate carboxylases [PDB: 1gk8], B) a tryptophan in the eukaryotic-type carbonic anhydrases [PDB: 1ca2] and C) a serine in the legume lectins [PDB: 2ltn]. D) An aspartate in the cyclodextrin glycosyltransferases forms a hydrogen bond to an edge strand as well as forming local interactions to a type 12:12 β-hairpin [PDB: 1qhp]. Two examples of polar residues forming hydrogen bonds with mainchain atoms in β-hairpins via a local interaction including, E) a cysteine in the azurin/plastocyanin family and F) a serine in the glycosyl hydrolase family 11 [PDB: 1xnb].