title: The oxygen binding site of cytochrome oxidase. Structural predictions on subunit I from amino acid sequences.
abstract: Analyses of heme-attached amino acid sequences in known hemoprotein superfamilies provide a basis for prediction of such sequences in hemoproteins of unknown three-dimensional structure. Among 11 histidine residues conserved in subunit I of 3 mammalian and 2 fungal cytochrome oxidases the sequence around His-233 (human) is the most conserved and shows remarkable similarity to the sequence of the oxygen binding site in globins. Furthermore, the gene coding for subunit I in Saccharomyces cerevisiae and the gene for leghemoglobin in soybean are both split by introns right after these similar histidine sequences. The predicted distal histidine sequence of subunit I provides for heme a3 and Cua3 binding and has an extraordinarily high content of aromatic residues. These aromatic groups may serve as a molecular electron capacitor. Transmembrane sequences and electron transfer sequences are proposed.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002417:Cattle; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D046911:Macromolecular Substances; D051379:Mice; D009492:Neurospora crassa; D010100:Oxygen / Q000378:metabolism*; D012441:Saccharomyces cerevisiae
chemical_list: D046911:Macromolecular Substances; D003576:Electron Transport Complex IV; D010100:Oxygen