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Current Protein & Peptide Science
ISSN (Print): 1389-2037
ISSN (Online): 1875-5550
VOLUME: 9
ISSUE: 6
DOI: 10.2174/138920308786733895      Price:  $58









The Hemoglobins of Fishes Living at Polar Latitudes - Current Knowledge on Structural Adaptations in a Changing Environment

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Author(s): Cinzia Verde, Alessandro Vergara, Lelio Mazzarella and Guido di Prisco
Pages 578-590 (13)
Abstract:
Fishes thriving in polar habitats offer many opportunities for comparative approaches to understanding protein adaptations to temperature. Notothenioidei, the dominant suborder in the Antarctic Ocean, have evolved reduction of hemoglobin concentration and multiplicity, perhaps as a consequence of temperature stability and other environmental parameters. In the icefish family, the blood pigment is absent. In contrast, similar to other acanthomorph teleosts, Arctic fish, thriving in a more complex oceanographic system, have maintained higher hemoglobin multiplicity and a highly diversified globin system in response to environmental variability and/or variations in metabolic demands. This review summarises the current knowledge on the structure, function and phylogeny of hemoglobins of fish living in polar habitats. On the basis of crystallographic analysis, a novel guideline to the interpretation of the Root effect in terms of a threestate model is suggested, implying the accessibility of an R/T intermediate quaternary structure, frequently observed in Antarctic fish hemoglobins. The occurrence of bis-histidyl and penta-coordinate states in ferric forms of polar fish hemoglobins suggests additional redox properties.
Keywords:
hemoglobin, polar fish, evolution, Root effect, X-ray structure
Affiliation:
Institute of Protein Biochemistry, CNR, Via Pietro Castellino 111, 80131 Naples Italy.