The extracellular hemoglobin of Glossoscolex paulistus (HbGp) has an extraordinary molecular mass of 3.6 MDa, with its oligomeric structure arranged as two superposed hexagonal discs forming a "bracelet". The quaternary structure of HbGp has 144 globin chains and 36 non-globin chains (named linkers). The HbGp dissociates in alkaline pH and in the presence of high surfactant concentrations, at 25 oC. Recent studies on the thermal stability of HbGp at different pH values, in the absence and presence of SDS and CTAC, using CD, SAXS and DLS techniques has provided interesting information about denaturation and aggregation processes for HbGp. However, structural changes, iron oxidation and the kinetics of aggregation processes for HbGp, in the presence and absence of surfactant, remain practically unknown. In this context, the present postdoctoral project proposes a further investigation of the kinetics of aggregation for oxy- and cyanomet-HbGp, in the absence and presence of SDS and CTAC, at different temperatures, by DLS. We also propose the use of new techniques, such as FTIR and fluorescence to investigate structural changes during the thermal denaturation of oxy- and cyanomet-HbGp, in the absence and presence of surfactant at acidic and neutral pH. The investigation of the dicátion salts, such as MgCl2 and CaCl2, and the monocation salt, NaCl, effects on the thermal stability of HbGp at pH 7.0, monitored by SAXS is also proposed. The electroanalytical technique of cyclic voltammetry to monitor the process of denaturation of oxy- and cyanomet-HbGp, induced by guanidine chloride and urea at pH 7.0, at 25 oC is also our focus. The use of these different techniques will contribute to improve the knowledge about the oligomeric dissociation, denaturation and aggregation phenomena for this giant hemoglobin, which has been studied by our group of Molecular Biophysics, at Institute of Chemistry of São Carlos (IQSC) for several years.
News published in Agência FAPESP Newsletter about the scholarship: