pH effect upon HbGp oligomeric stability: characterization of the dissociated species by AUC and DLS studies

Autor(es)

Carvalho, Francisco Adriano O. ^[1] ; Carvalho, Jose Wilson P. ^[1] ; Alves, Fernanda Rosa ^[1] ; Tabak, Marcel ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: International Journal of Biological Macromolecules; v. 59, p. 333-341, AUG 2013.
• Citações Web of Science: 13

Resumo

Glossoscolex paulistus (HbGp) extracellular hemoglobin is a giant oligomeric protein. It is constituted by 144 heme containing subunits and non-heme structures (linkers), with a total molecular mass of 3.6 MDa. AUC and DLS studies were developed for three HbGp forms, oxy-, met- and cyanomet-, at several pH values, in order to characterize the species in solution upon oligomeric dissociation. Isolated SEC fractions, trimer and dodecamer, are less stable as compared to the whole oxy-HbGp. The monomer d displays a large thermal stability up to 59 degrees C. Hydrodynamic properties of the isolated subunits are very similar to those described for them in the whole protein, in the presence of urea or at pH 10.0. The degree of HbGp oligomeric dissociation, in alkaline pH, depends significantly on the iron oxidation state. Also on the ligand coordinated to the heme iron. Thus, at pH 8.0, the oxy-HbGp is partially dissociated, while the metform is fully dissociated. The cyanomet-HbGp remains undissociated. Our present results show that the effect of pH on the HbGp oligomeric stability is similar to that associated to the urea-induced unfolding. Simultaneous use of AUC and DLS allowed the characterization of the species in the SEC fractions of isolated HbGp subunits. (C) 2013 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 09/17261-6 - Estudo da estabilidade oligomérica da hemoglobina extracellular gigante de Glossoscolex paulistus (HbGp) na presença de agentes caotrópicos, surfactantes e caracterização das subunidades.
• Beneficiário: Francisco Adriano de Oliveira Carvalho
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 11/09863-6 - Análise da interação da hemoglobina extracelular gigante de Glossoscolex paulistus (HbGp) com surfactantes iônicos por calorimetria de titulação isotérmica
• Beneficiário: Fernanda Rosa Alves
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 10/09719-0 - Estudos dos efeitos de surfactantes, do estado de oxidação do ferro e do pH do meio na estabilidade térmica da hemoglobina extracelular gigante de Glossoscolex paulistus (HbGp) na forma íntegra e de suas subunidades monômero d e trímero ABC
• Beneficiário: José Wilson Pires Carvalho
• Modalidade de apoio: Bolsas no Brasil - Doutorado