title: Conformational stability of peanut agglutinin using small angle X-ray scattering.
abstract: In this work, quaternary conformational studies of peanut agglutinin (PNA) have been carried out using small-angle X-ray scattering (SAXS). PNA was submitted to three different conditions: pH variation (2.5, 4.0, 7.4 and 9.0), guanidine hydrochloride presence (0.5-2M) at each pH value, and temperature ranging from 25 to 60°C. All experiments were performed in the absence and presence of T-antigen to evaluate its influence on the lectin stability. At room temperature and pH 4.0, 7.4 and 9.0, the SAXS curves are consistent with the PNA scattering in its crystallographic native homotetrameric structure, with monomers in a jelly roll fold, associated by non-covalent bonds resulting in an open structure. At pH 2.5, the results indicate that PNA tends to dissociate into smaller sub-units, as dimers and monomers, followed by a self-assembling into larger aggregates. Furthermore, the conformational stability under thermal denaturation follows the pH sequence 7.4>9.0>4.0>2.5. Such results are consistent with the conformational behavior found upon GndHCl influence. The presence of T-antigen does not affect the protein quaternary structure in all studied systems within the SAXS resolution.
authors.affiliation: Escola de Artes, Ciências e Humanidades da Universidade de São Paulo, Av. Arlindo Bettio, 1000 Ermelino Matarazzo, CEP 03828-000 São Paulo, SP, Brazil. pcampana@usp.br
authors.forename: Patricia Targon
authors.initials: PT
authors.lastname: Campana
authors.forename: Leandro Ramos Souza
authors.initials: LR
authors.lastname: Barbosa
authors.forename: Rosangela
authors.initials: R
authors.lastname: Itri
mesh_terms: D000957:Antigens, Viral, Tumor / Q000378:metabolism; D019791:Guanidine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D019887:Peanut Agglutinin / Q000737:chemistry*; D011487:Protein Conformation; D053838:Scattering, Small Angle; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000957:Antigens, Viral, Tumor; D019887:Peanut Agglutinin; D019791:Guanidine