Thermal denaturation and aggregation of hemoglobin of Glossoscolex paulistus in acid and neutral media

Autor(es)

Carvalho, Jose Wilson P. ^[1] ; Carvalho, Francisco A. O. ^[1] ; Santiago, Patricia S. ^{[2, 1]} ; Tabak, Marcel ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Estadual Paulista, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: International Journal of Biological Macromolecules; v. 54, p. 109-118, MAR 2013.
• Citações Web of Science: 8

Resumo

The thermal denaturation and aggregation of the HbGp, in the oxy- and cyanomet-forms, was investigated by DSC, AUC, DLS, optical absorption and CD, in the pH range from 5.0 to 7.0. Oxy-HbGp has a denaturation process partially reversible and dependent on the temperature. DSC melting curve is characterized by a single peak with T-c value of 333.4 +/- 0.2 K for oxy-HbGp, while two peaks with T-c values of 332.2 +/- 0.1 and 338.4 +/- 0.2 K are observed for cyanomet-HbGp, at pH 7.0. In acidic pH oxy- and cyanomet-HbGp are more stable showing higher T-c values and aggregation. AUC data show that, HbGp, at pH 7.0, upon denaturation, remains undissociated at 323 K, presenting oligomeric dissociation at 333 (12 +/- 3% of tetramer and 88 +/- 5% of whole HbGp) and 343 K (70 +/- 5% of monomer and 30 +/- 2% of trimer). DLS data show that the lag period before aggregation is dependent on the temperature and HbGp concentration. Optical absorption and CD results show that the increase of temperature leads to the oxy-HbGp oxidation and aggregation, above 331 K, in acidic pH. CD data, for HbGp, present a greater thermal stability in acid medium than at neutral pH, with similar T-c values for both oxidation forms. Our data are consistent with previous studies and represents an advance in understanding the thermal stability of oligomeric HbGp structure. (c) 2012 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: 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