The oxygen binding properties of hemocyanin from the mollusk Concholepas concholepas
Author
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González, Andrea
Author
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Nova, Esteban
Author
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Campo, Miguel del
Author
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Manubens, Augusto
Author
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Ioannes, Alfredo de
Author
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Ferreira Parker, Jorge
Author
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Becker, María Inés
Admission date
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2018-06-12T22:41:32Z
Available date
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2018-06-12T22:41:32Z
Publication date
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2017
Cita de ítem
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BBA Proteins and Proteomics 1865 (2017) 1746–1757
es_ES
Identifier
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http://dx.doi.org/10.1016/j.bbapap.2017.08.017
Identifier
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https://repositorio.uchile.cl/handle/2250/148826
Abstract
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Hemocyanins have highly conserved copper-containing active sites that bind oxygen. However, structural differences
among the hemocyanins of various mollusks may affect their physicochemical properties. Here, we
studied the oxygen-binding cooperativity and affinity of Concholepas concholepas hemocyanin (CCH) and its two
isolated subunits over a wide range of temperatures and pH values. Considering the differences in the quaternary
structures of CCH and keyhole limpet hemocyanin (KLH), we hypothesized that the heterodidecameric CCH has
different oxygen-binding parameters than the homodidecameric KLH. A novel modification of the polarographic
method was applied in which rat liver submitochondrial particles containing cytochrome c oxidase were introduced
to totally deplete oxygen of the test solution using ascorbate as the electron donor. This method was
both sensitive and reproducible. The results showed that CCH, like other hemocyanins, exhibits cooperativity,
showing an inverse relationship between the oxygen-binding parameters and temperature. According to their
Hill coefficients, KLH has greater cooperativity than CCH at physiological pH; however, CCH is less sensitive to
pH changes than KLH. Appreciable differences in binding behavior were found between the CCH subunits: the
cooperativity of CCH-A was not only almost double that of CCH-B, but it was also slightly superior to that of
CCH, thus suggesting that the oxygen-binding domains of the CCH subunits are different in their primary
structure. Collectively, these data suggest that CCH-A is the main oxygen-binding domain in CCH; CCH-B may
play a more structural role, perhaps utilizing its surprising predisposition to form tubular polymers, unlike CCHA,
as demonstrated here using electron microscopy.
es_ES
Patrocinador
dc.description.sponsorship
FONDECYT Grants 1050150, 1110651 and 1151337
Grant No. 1061086 from
FONDECYT and ACT 29 Anillo Bicentenario awarded