title: Hemoglobins of reptiles. The primary structure of the major and minor hemoglobin component of adult Western Painted Turtle (Chrysemys picta bellii).
abstract: Red blood cells of adult Western Painted Turtles (Chrysemys picta bellii) contain two hemoglobin components: HbA (alpha A2 beta 2) and HbD (alpha D2 beta 2). We present the complete amino-acid sequences of the alpha A-chains from the major component and of the beta-chains common to both components. Structural features are discussed with respect to the animals extreme tolerance of severe hypoxic conditions during hibernation which is accompanied by a high oxygen affinity of the hemoglobin. The strong ATP dependence of Western Painted Turtle hemoglobin oxygen affinity is contrasted by the loss of one ATP-binding site, beta 143(H21)-Arg----Leu. The primary structure of the beta-chains excludes an allosteric control mechanism by hydrogencarbonate as it was found in crocodiles. Except in turtles a hemoglobin pattern with HbA and HbD sharing the same beta-subunits has been found only in birds. In comparison to other vertebrate hemoglobins there is a surprising similarity of the sequences to those of bird hemoglobins. alpha A- as well as alpha D-chains show larger homologies to chains of the same type in different species than alpha A- and alpha D-chains to each other in the same species. This indicates a duplication of the alpha-gene preceding the divergence of turtles and birds.
authors: Max-Planck-Institut für Biochemie, Abteilung Proteinchemie, Martinsried bei München.
authors: K P
authors: KP
authors: Rücknagel
authors: G
authors: G
authors: Braunitzer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004912:Erythrocytes / Q000032:analysis; D006441:Hemoglobin A / Q000302:isolation & purification; D006455:Hemoglobins, Abnormal / Q000302:isolation & purification; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis; D013045:Species Specificity; D014357:Trypsin; D014426:Turtles / Q000097:blood*
chemical_list: D006455:Hemoglobins, Abnormal; D046911:Macromolecular Substances; D010446:Peptide Fragments; C032001:hemoglobin D; D006441:Hemoglobin A; D014357:Trypsin