Denaturant effects on HbGp hemoglobin as monitored by 8-anilino-1-naphtalene-sulfonic acid (ANS) probe

Autor(es)

Barros, Ana E. B. ^[1] ; Carvalho, Francisco A. O. ^[1] ; Alves, Fernanda R. ^[1] ; Carvalho, Jose W. P. ^{[1, 2]} ; Tabak, Marcel ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-05508 Sao Paulo, SP - Brazil

^[2] Univ Estado Mato Grosso, Cuiaba, MT - Brazil

• Tipo de documento: Artigo Científico
• Fonte: International Journal of Biological Macromolecules; v. 74, p. 327-336, MAR 2015.
• Citações Web of Science: 6

Resumo

Glossoscolex paulistus extracellular hemoglobin (HbGp) stability has been monitored in the presence of denaturant agents. 8-Anilino-1-naphtalene-sulfonic acid (ANS) was used, and spectroscopic and hydrodynamic studies were developed. Dodecyltrimethylammonium bromide (DTAB) induces an increase in ANS fluorescence emission intensity, with maximum emission wavelength blue-shifted from 517 to 493 nm. Two transitions are noticed, at 2.50 and 9.50 mmol/L of DTAB, assigned to ANS interaction with pre-micellar aggregates and micelles, respectively. In oxy-HbGp, ANS binds to protein sites less exposed to solvent, as compared to DTAB micelles. In DTAB HbGp ANS ternary system, at pH 7.0, protein aggregation, oligomeric dissociation and unfolding were observed, while, at pH 5.0, aggregation is absent. DTAB induced unfolding process displays two transitions, one due to oligomeric dissociation and the second one, probably, to the denaturation of dissociated subunits. Moreover, guanidine hydrochloride and urea concentrations above 1.5 and 4.0 mol/L, respectively, induce the full HbGp denaturation, with reduction of ANS-bound oxy-HbGp hydrophobic patches, as noticed by fluorescence quenching up to 1.0 and 5.0 mol/L of denaturants. Our results show clearly the differences in probe sensitivity to the surfactant, in the presence and absence of protein, and new insights into the denaturant effects on HbGp unfolding. (C) 2014 Elsevier B.V. All rights reserved. (AU)

• 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: 13/09829-8 - Estudos biofísicos e estruturais da hemoglobina extracelular de Glossoscolex paulistus, e das suas subunidades monômero d e dodecâmero (abcd)3.
• Beneficiário: Francisco Adriano de Oliveira Carvalho
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado