title: Novel mechanism for high-altitude adaptation in hemoglobin of the Andean frog Telmatobius peruvianus.
abstract: In contrast to birds and mammals, no information appears to be available on the molecular adaptations for O(2) transport in high-altitude ectothermic vertebrates. We investigated Hb of the aquatic Andean frog Telmatobius peruvianus from 3,800-m altitude as regards isoform differentiation, sensitivity to allosteric cofactors, and primary structures of the alpha- and beta-chains, and we carried out comparative O(2)-binding measurements on Hb of lowland Xenopus laevis. The three T. peruvianus isoHbs show similar functional properties. The high O(2) affinity of the major component results from an almost complete obliteration of chloride sensitivity, which correlates with two alpha-chain modifications: blockage of the NH(2)-terminal residues and replacement by nonpolar Ala of polar residues Ser and Thr found at position alpha131(H14) in human and X. leavis Hbs, respectively. The data indicate adaptive significance of alpha-chain chloride-binding sites in amphibians, in contrast to human Hb where chloride appears mainly to bind in the cavity between the beta-chains. The findings are discussed in relation to other strategies for high-altitude adaptations in amphibians.
authors.affiliation: Department of Zoophysiology, University of Aarhus, 131 C. F. Møllers Alle, DK 8000 Aarhus C, Denmark. roy.weber@biology.au.dk
authors.forename: Roy E
authors.initials: RE
authors.lastname: Weber
authors.forename: Hrvoj
authors.initials: H
authors.lastname: Ostojic
authors.forename: Angela
authors.initials: A
authors.lastname: Fago
authors.forename: Sylvia
authors.initials: S
authors.lastname: Dewilde
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Van Hauwaert
authors.forename: Luc
authors.initials: L
authors.lastname: Moens
authors.forename: Carlos
authors.initials: C
authors.lastname: Monge
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000531:Altitude; D000595:Amino Acid Sequence; D000818:Animals; D001001:Anura / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006454:Hemoglobins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D010101:Oxygen Consumption / Q000502:physiology; D013045:Species Specificity; D013329:Structure-Activity Relationship; D014982:Xenopus laevis
chemical_list: D006454:Hemoglobins