title: Functional characterization of the single hemoglobin of the migratory bird Ciconia ciconia.
abstract: Hemolysate from white stork displayed a single hemoglobin component, thus resulting into two bands and two globin peaks in dissociating PAGE and reversed phase-HPLC, respectively. Stripped hemoglobin showed an oxygen affinity higher than that of human HbA, a small Bohr effect, and a cooperative oxygen binding. A small decrease of oxygen affinity, of the same extent in all the pH range examined, was observed by addition of chloride, thus indicating an unusual chloride-independent Bohr effect (DeltalogP50/Deltalog pH=-0.24). Saturating amounts of inositol hexakisphosphate, largely decreased hemoglobin-oxygen affinity (DeltalogP(50)=1.17 at pH 7.0), and increased the extent of its Bohr effect (DeltalogP50/DeltalogpH=-0.45). The phosphate binding curve allowed to measure a very high overall binding constant (K=1.18 x 10(5) M(-1)). The effect of temperature on the oxygen affinity was measured, and the enthalpy change of oxygenation resulted almost independent on pH. Structural-functional relationships are discussed by considering some amino acid residues situated at alpha1/beta1 and alpha1/beta2 interfaces, such as alpha38 and alpha89 positions. The presence of only one hemoglobin component, a rare event among birds, and its functional properties have been related to the physiological oxygen requirements of this soaring migrant bird and to its technique of flight during migration.
authors.affiliation: Dipartimento di Scienze Applicate ai Biosistemi, Università di Cagliari, Cittadella Universitaria, I-09042 Monserrato (CA) Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Manconi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Olianas
authors.forename: Maria T
authors.initials: MT
authors.lastname: Sanna
authors.forename: Irene
authors.initials: I
authors.lastname: Messana
authors.forename: Loredana
authors.initials: L
authors.lastname: Demurtas
authors.forename: Massimo
authors.initials: M
authors.lastname: Castagnola
authors.forename: Bruno
authors.initials: B
authors.lastname: Giardina
authors.forename: Mariagiuseppina
authors.initials: M
authors.lastname: Pellegrini
mesh_terms: D000818:Animals; D001717:Birds / Q000097:blood*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism*; D007525:Isoelectric Focusing; D010100:Oxygen / Q000378:metabolism; D011485:Protein Binding; D013053:Spectrophotometry; D013696:Temperature
chemical_list: D006454:Hemoglobins; D010100:Oxygen