title: Haemoglobin of the antarctic fish Pagothenia bernacchii. Amino acid sequence, oxygen equilibria and crystal structure of its carbonmonoxy derivative.
abstract: The Antarctic fish Pagothenia bernacchii has one major haemoglobin, Hb1 (over 95% of the total blood content). Hb1 has a strong alkaline Bohr effect and at low pH exhibits the reduced ligand affinity and co-operativity that comprise the Root effect. We have determined the complete amino acid sequence of P. bernacchii Hb1 and also the structure of its carbonmonoxy derivative by X-ray crystallography, to a resolution of 2.5 A. The crystallographic R-factor of the refined structure is 18%. The three-dimensional structure of this fish haemoglobin is similar to that of human haemoglobin A, with a root-mean-square difference in main-chain atom positions of 1.4 A after superimposition of the two structures, despite only 48% homology of their amino acid sequences (including insertion of a single residue in the CD region of the fish alpha-chain). Large structural differences occur only at the N and C termini of both the alpha- and beta-chains. Neither these nor other smaller structural differences provide any obvious explanation of the Root effect of this or other fish haemoglobins.
authors.affiliation: Institute of Protein Biochemistry and Enzymology, C.N.R., Naples, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Camardella
authors.forename: C
authors.initials: C
authors.lastname: Caruso
authors.forename: R
authors.initials: R
authors.lastname: D'Avino
authors.forename: G
authors.initials: G
authors.lastname: di Prisco
authors.forename: B
authors.initials: B
authors.lastname: Rutigliano
authors.forename: M
authors.initials: M
authors.lastname: Tamburrini
authors.forename: G
authors.initials: G
authors.lastname: Fermi
authors.forename: M F
authors.initials: MF
authors.lastname: Perutz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002248:Carbon Monoxide / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D005399:Fishes; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism; D016415:Sequence Alignment; D014961:X-Ray Diffraction
chemical_list: D006454:Hemoglobins; D002248:Carbon Monoxide; D010100:Oxygen