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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Glossoscolex paulistus Extracellular Hemoglobin (HbGp) Oligomeric Dissociation upon Interaction with Sodium Dodecyl Sulfate: Isothermal Titration Calorimetry (ITC)

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Alves, Fernanda Rosa [1] ; Carvalho, Francisco Adriano O. [1] ; Carvalho, Jose Wilson P. [1, 2] ; Tabak, Marcel [1]
Total Authors: 4
[1] Univ Sao Paulo, Dept Quim & Fis Mol, Inst Quim Sao Carlos, Sao Carlos, SP - Brazil
[2] Univ Estado Mato Grosso, Barra Do Bugres, MT - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Biopolymers; v. 101, n. 10, p. 1065-1076, OCT 2014.
Web of Science Citations: 4

Annelid erythrocruorins are respiratory proteins with high cooperativity and low autoxidation rates. The giant extracellular hemoglobin of the earthworm, Glossoscolex paulistus (HbGp), has a molecular mass of 3.6 MDa. In this work, isothermal titration calorimetry (ITC), together with DLS and fluorescence emission have been used to investigate the interaction of SDS with the HbGp in the oxy-form, at pH 7.0. Our ITC and DLS results show that addition of SDS induces oxy-HbGp oligomeric dissociation, while a small amount of protein aggregation is observed only by DLS. Moreover, the oligomeric dissociation process is favored at lower protein concentrations. The temperature effect does not influence significantly the interaction of SDS with the hemoglobin, due to the similarities presented by the critical aggregation concentration (cac) and critical micelle concentration (cmc') for the mixtures. The increase of oxy-HbGp concentration leads to a slight variation of the cac values for the SDS-oxyHbGp mixture, attributed mainly to the noncooperative electrostatic binding of surfactant to protein. However, the cmc' values increase considerably, associated to a more cooperative hydrophobic binding. Complementary pyrene fluorescence emission studies show formation of pre-micellar structures of the mixture already at lower SDS concentrations. This study opens the possibility of the evaluation of the surfactant effect on the hemoglobin stability by ITC, which is made for the first time with this extracellular hemoglobin. (C)2014 Wiley Periodicals, Inc. (AU)

FAPESP's process: 13/09829-8 - Biophysical and structural studies of extracellular hemoglobin of Glossoscolex paulistus, and its monomer d and dodecamer (abcd)3 subunits.
Grantee:Francisco Adriano de Oliveira Carvalho
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 11/09863-6 - Analysis of giant extracellular hemoglobin from Glossoscolex paulistus (HbGp) and ionic surfactants interaction by isothermal titration calorimetry
Grantee:Fernanda Rosa Alves
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 13/09349-6 - Thermal and kinetic stability of the giant extracellular hemoglobin of Glossoscolex paulistus (HbGp): effects of surfactants, salts, urea, iron heme oxidation state and pH.
Grantee:José Wilson Pires Carvalho
Support type: Scholarships in Brazil - Post-Doctorate