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Oxygen binding properties of non‐mammalian nerve globins
Author(s) -
Hundahl Christian,
Fago Angela,
Dewilde Sylvia,
Moens Luc,
Hankeln Tom,
Burmester Thorsten,
Weber Roy E.
Publication year - 2006
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2006.05158.x
Subject(s) - neuroglobin , hexacoordinate , bohr effect , globin , biology , myoglobin , hemoglobin , vertebrate , aplysia , annelid , danio , biophysics , anatomy , chemistry , biochemistry , evolutionary biology , zebrafish , oxygen–haemoglobin dissociation curve , gene , organic chemistry , silicon
Oxygen‐binding globins occur in the nervous systems of both invertebrates and vertebrates. While the function of invertebrate nerve haemoglobins as oxygen stores that extend neural excitability under hypoxia has been convincingly demonstrated, the physiological role of vertebrate neuroglobins is less well understood. Here we provide a detailed analysis of the oxygenation characteristics of nerve haemoglobins from an annelid ( Aphrodite aculeata ), a nemertean ( Cerebratulus lacteus ) and a bivalve ( Spisula solidissima ) and of neuroglobin from zebrafish ( Danio rerio ). The functional differences have been related to haem coordination: the haem is pentacoordinate (as in human haemoglobin and myoglobin) in A. aculeata and C. lacteus nerve haemoglobins and hexacoordinate in S. solidissima nerve haemoglobin and D. rerio neuroglobin. Whereas pentacoordinate nerve globins lacked Bohr effects at all temperatures investigated and exhibited large enthalpies of oxygenation, the hexacoordinate globins showed reverse Bohr effects (at least at low temperature) and approximately twofold lower oxygenation enthalpies. Only S. solidissima nerve haemoglobin showed apparent cooperativity in oxygen binding, suggesting deoxygenation‐linked self‐association of the monomeric proteins. These results demonstrate a remarkable diversity in oxygenation characteristics of vertebrate and invertebrate nerve haemoglobins that clearly reflect distinct physiological roles.