title: Sodium dodecyl sulfate (SDS) effect on the thermal stability of oxy-HbGp: dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) studies.
abstract: Glossoscolex paulistus (HbGp) hemoglobin is an oligomeric protein, presenting a quaternary structure constituted by 144 globin and 36 non-globin chains (named linkers) with a total molecular mass of 3.6 MDa. SDS effects on the oxy-HbGp thermal stability were studied, by DLS and SAXS, at pH 5.0, 7.0 and 9.0. DLS and SAXS data show that the SDS-oxy-HbGp interactions induce a significant decrease of the protein thermal stability, with the formation of larger aggregates, at pH 5.0. At pH 7.0, oxy-HbGp undergoes complete oligomeric dissociation, with increase of temperature, in the presence of SDS. Besides, oxy-HbGp 3.0mg/mL, pH 7.0, in the presence of SDS, has the oligomeric dissociation process reduced as compared to 0.5mg/mL of protein. At pH 9.0, oxy-HbGp starts to dissociate at 20 °C, and the protein is totally dissociated at 50 °C. The thermal dissociation kinetic data show that oxy-HbGp oligomeric dissociation at pH 7.0, in the presence of SDS, is strongly dependent on the protein concentration. At 0.5mg/mL of protein, the oligomeric dissociation is complete and fast at 40 and 42 °C, with kinetic constants of (2.1 ± 0.2) × 10(-4) and (5.5 ± 0.4) × 10(-4) s(-1), respectively, at 0.6 mmol/L SDS. However, at 3.0mg/mL, the oligomeric dissociation process starts at 46 °C, and only partial dissociation, accompanied by aggregates formation is observed. Moreover, our data show, for the first time, that, for 3.0mg/mL of protein, the oligomeric dissociation, denaturation and aggregation phenomena occur simultaneously, in the presence of SDS. Our present results on the surfactant-HbGp interactions and the protein thermal unfolding process correspond to a step forward in the understanding of SDS effects.
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil.
authors.forename: José Wilson P
authors.initials: JW
authors.lastname: Carvalho
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil.
authors.forename: Fernanda Rosa
authors.initials: FR
authors.lastname: Alves
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil; Universidade Estadual de Maringá, Paraná, Brazil.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Batista
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil.
authors.forename: Francisco Adriano O
authors.initials: FA
authors.lastname: Carvalho
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil; Campus Experimental de Registro, Universidade Estadual Paulista "Júlio de Mesquita Filho", Registro, SP, Brazil.
authors.forename: Patrícia S
authors.initials: PS
authors.lastname: Santiago
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil. Electronic address: marcel@sc.usp.br.
authors.forename: Marcel
authors.initials: M
authors.lastname: Tabak
mesh_terms: D057446:Hydrodynamics; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D010108:Oxyhemoglobins / Q000737:chemistry*; D010316:Particle Size; D055550:Protein Stability / Q000187:drug effects; D012542:Scattering, Radiation; D053838:Scattering, Small Angle; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology*; D013501:Surface-Active Agents / Q000494:pharmacology; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D010108:Oxyhemoglobins; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate
keywords: DLS; Glossoscolex paulistus; Oligomeric dissociation; SAXS; SDS; Thermal stability