Figure 7From: On the evolutionary conservation of hydrogen bonds made by buried polar amino acids: the hidden joists, braces and trusses of protein architectureExamples of hydrogen bond interactions from conserved, buried residues to mainchain atoms in centre strands. 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. A) A serine residue within a coil forming hydrogen bonds to two strands that have deviated away from each other in the haloperoxidases [PDB: 1b6g]. Examples of polar residues that form hydrogen bonds to an adjacent strand that extends further than its neighbour, including serines in B) the pancreatic ribonuclease family [PDB: 7rsa] and C) the cyclodextrin glycosyltransferases [PDB: 1qhp], D) a threonine in the aldehyde oxide and xanthine dehydrogenases (domains 1&2) [PDB: 1fo4] and E) a cysteine in the papain family cysteine proteinase [PDB: 1mem]. F) Two threonines that form hydrogen bonds to each other's mainchain amide atoms as well as atoms within strands (one central, one edge) in the aspartic proteinases [PDB: 3app].Back to article page