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Effects of surfactants, iron oxidation state and medium pH upon the thermal stability of giant extracellular hemoglobin of Glossoscolex paulistus in its native oligomeric form and for trimeric ABC and monomeric d globin subunits

Grant number: 10/09719-0
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): October 01, 2010
Effective date (End): August 31, 2013
Field of knowledge:Biological Sciences - Biophysics - Molecular Biophysics
Principal researcher:Marcel Tabak
Grantee:José Wilson Pires Carvalho
Home Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Giant extracellular hemoglobin of Glossocolex paulistus (HbGp) presents an extraordinary molecular mass of 3.6 MDa, organized in an oligomeric arrangement known as the "bracelet model", involving an hexagonal bilayer as monitored by electron microscopy. Its quaternary structure is composed of 144 globin chains bearing an heme group, and 36 linker chains lacking the heme group. It has a high oxygen cooperativity and oligomeric stability, as well as a significant re-association capacity. HbGp dissociates at alkaline pH and in the presence of surfactants, originating smaller subunits. Evaluation of the kinetic dissociation constants, of the size and the form of the particles corresponding to different hemoglobin iron oxidation states, in the absence and in the presence of surfactants, can give relevant information regarding the oligomeric structure and stability of the protein. The present Ph.D. project proposes to study the protein thermal stability, the dissociation and/or denaturation of HbGp in the oxy-, met-, and cyanomet- forms, at different pH values, and in the presence of surfactants. These studies will allow to evaluate the dissociation mechanisms, making it possible to obtain a deeper understanding regarding the subunit stoichiometry upon oligomeric formation. The thermal stability of the native protein as well as its stability related to heme oxidation processes, and that regarding the globin trimeric abc and monomeric d subunits will also be evaluated. To obtain this information several spectroscopic and structural techniques will be used in this study, such as optical absorption spectroscopy, circular dichroism (CD), dynamic light scattering (DLS) and small angle X-ray scattering (SAXS), as well as differential scanning calorimetry (DSC). The use of these biophysical and physico-chemical techniques, simultaneously, will contribute to the deepening of the available knowledge and characterization of this giant hemoglobin, which has been under investigation in our laboratory for the past several years. (AU)

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Scientific publications (7)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
CARVALHO, FRANCISCO ADRIANO O.; CARVALHO, JOSE WILSON P.; SANTIAGO, PATRICIA S.; TABAK, MARCEL. Further characterization of the subunits of the giant extracellular hemoglobin of Glossoscolex paulistus (HbGp) by SDS-PAGE electrophoresis and MALDI-TOF-MS. Process Biochemistry, v. 46, n. 11, p. 2144-2151, . (09/17261-6, 10/09719-0)
CARVALHO, JOSE WILSON P.; SANTIAGO, PATRICIA S.; BATISTA, TATIANA; GARRIDO SALMON, CARLOS ERNESTO; BARBOSA, LEANDRO R. S.; ITRI, ROSANGELA; TABAK, MARCEL. On the temperature stability of extracellular hemoglobin of Glossoscolex paulistus, at different oxidation states: SAXS and DLS studies. Biophysical Chemistry, v. 163, p. 44-55, . (10/09719-0)
CARVALHO, FRANCISCO A. O.; CARVALHO, JOSE WILSON P.; SANTIAGO, PATRICIA S.; TABAK, MARCEL. Urea-induced unfolding of Glossoscolex paulistus hemoglobin, in oxy- and cyanomet-forms: A dissociation model. International Journal of Biological Macromolecules, v. 52, p. 340-348, . (09/17261-6, 10/09719-0)
CARVALHO, JOSE WILSON P.; ALVES, FERNANDA ROSA; BATISTA, TATIANA; CARVALHO, FRANCISCO ADRIANO O.; SANTIAGO, PATRICIA S.; TABAK, MARCEL. Sodium dodecyl sulfate (SDS) effect on the thermal stability of oxy-HbGp: Dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) studies. COLLOIDS AND SURFACES B-BIOINTERFACES, v. 111, p. 561-570, . (09/17261-6, 10/09719-0, 11/09863-6)
CARVALHO, FRANCISCO ADRIANO O.; CARVALHO, JOSE WILSON P.; ALVES, FERNANDA ROSA; TABAK, MARCEL. pH effect upon HbGp oligomeric stability: characterization of the dissociated species by AUC and DLS studies. International Journal of Biological Macromolecules, v. 59, p. 333-341, . (09/17261-6, 10/09719-0, 11/09863-6)
CARVALHO, FRANCISCO A. O.; CARVALHO, JOSE W. P.; BIAZIN, EZER; SANTIAGO, PATRICIA S.; TABAK, MARCEL. Characterization of Rhinodrilus alatus hemoglobin (HbRa) and its subunits: Evidence for strong interaction with cationic surfactants DTAB and CTAC. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY, v. 167, p. 23-29, . (09/17261-6, 10/09719-0)
CARVALHO, JOSE WILSON P.; CARVALHO, FRANCISCO A. O.; SANTIAGO, PATRICIA S.; TABAK, MARCEL. Thermal denaturation and aggregation of hemoglobin of Glossoscolex paulistus in acid and neutral media. International Journal of Biological Macromolecules, v. 54, p. 109-118, . (09/17261-6, 10/09719-0)
Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
CARVALHO, José Wilson Pires. Thermal stability studies of giant extracellular hemoglobin Glossoscolex paulistus (HbGp): effect of oxidation state of the heme group iron, pH and the presence of surfactant. 2013. Doctoral Thesis - Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT) São Carlos.

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