title: The hemoglobin system of the serpent eel Ophisurus serpens: structural and functional characterization.
abstract: The hemoglobin system of the serpent eel Ophisurus serpens was structurally and functionally characterized with the aim of comparing it to the hemoglobin system of other fish species, as oxygen loading under the severe habitat conditions experienced by O. serpens could have necessitated specific adaptation mechanisms during evolution. The hemoglobin system of O. serpens includes one cathodic and four anodic components. The molecular mass of the α and β chains of the cathodic component as well as the 2 α and 4 β of the anodic components were determined. Analysis of the intact α and β chains from cathodic hemoglobin and their proteolytic digestion products by high-resolution MS and MS/MS experiments resulted in 92 and 95 % sequence coverage of the α and β globins, respectively. The oxygen binding properties of both hemoglobin components were analyzed with respect to their interactions with their physiological effectors. Stripped cathodic hemoglobin displayed the highest oxygen affinity among Anguilliformes with no significant effect of pH on O2-affinity. In the presence of both chloride and organic phosphates, O2-affinity was strongly reduced, and cooperativity was enhanced; moreover, cathodic hemoglobin contains two indistinguishable GTP-binding sites. Stripped anodic hemoglobins exhibited both low O2-affinity and low cooperativity and a larger Bohr effect than cathodic hemoglobin. The cathodic hemoglobin of O. serpens and the corresponding component of Conger conger share the greatest structural and functional similarity among hemoglobin systems of Anguilliformes studied to date, consistent with their phylogenetic relationship.
authors: Department of Life and Environmental Sciences, University of Cagliari, Cittadella Universitaria, 09042, Monserrato, CA, Italy.
authors: Barbara
authors: B
authors: Manconi
authors: Mariagiuseppina
authors: M
authors: Pellegrini
authors: Irene
authors: I
authors: Messana
authors: Maria Teresa
authors: MT
authors: Sanna
authors: Massimo
authors: M
authors: Castagnola
authors: Federica
authors: F
authors: Iavarone
authors: Elisabetta
authors: E
authors: Coluccia
authors: Bruno
authors: B
authors: Giardina
authors: Alessandra
authors: A
authors: Olianas
mesh_terms: D000255:Adenosine Triphosphate / Q000097:blood; D000595:Amino Acid Sequence; D000818:Animals; D004524:Eels / Q000097:blood*; D004912:Erythrocytes / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000097:blood; D006454:Hemoglobins / Q000737:chemistry* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D016415:Sequence Alignment; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D006454:Hemoglobins; D010455:Peptides; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate
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