Carvalho, Jose Wilson P.Santiago, Patricia S. [UNESP]Batista, TatianaGarrido Salmon, Carlos ErnestoBarbosa, Leandro R. S.Itri, RosangelaTabak, Marcel2014-05-202014-05-202012-04-01Biophysical Chemistry. Amsterdam: Elsevier B.V., v. 163, p. 44-55, 2012.0301-4622http://hdl.handle.net/11449/108Glossoscolex paulistus hemoglobin (HbGp) was studied by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). DLS melting curves were measured for met-HbGp at different concentrations. SAXS temperature studies were performed for oxy-, cyanomet- and met-HbGp forms, at several pH values. At pH 5.0 and 6.0, the scattering curves are identical from 20 to 60 degrees C, and R-g is 108 angstrom, independent of the oxidation form. At pH 7.0, protein denaturation and aggregation occurs above 55 degrees C and 60 degrees C, for oxy and met-HbGp, respectively. Cyanomet-HbGp, at pH 7.0, is stable up to 60 degrees C. At alkaline pH (8.0-9.0) and higher temperature, an irreversible dissociation process is observed, with a decrease of R-g, D-max and I(0). Analysis by p(r), obtained from GNOM, and OLIGOMER, was used to fit the SAXS experimental scattering curves by a combination of theoretical curves obtained for HbLt fragments from the crystal structure. Our results show clearly the increasing contribution of smaller molecular weight fragments, as a function of increasing pH and temperature, as well as, the order of thermal stabilities: cyanomet-> oxy- > met-HbGp. (C) 2012 Elsevier B.V. All rights reserved.44-55engExtracellular hemoglobinGlossoscolex paulistusOligomeric dissociationThermal stabilityDLSSAXSArtigo10.1016/j.bpc.2012.02.004WOS:000303225900005Acesso restrito67053670106620870000-0002-6205-9441