Albumin-induced circular dichroism in Congo red: applications for studies of amyloid-like fibril aggregates and binding sites

dc.contributor.authorVasconcelos, Débora Naliati de [UNESP]
dc.contributor.authorXimenes, Valdecir Farias [UNESP]
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.description.abstractCongo red (CR), one of the most commonly used dyes for the identification of amyloid fibril aggregates, is also a ligand of native bovine serum albumin (BSA). Induced circular dichroism (ICD) is a phenomenon observed when a chiral compound induces chirality in an achiral one. Here, we study the spectral properties and analytical applications of ICD in Congo red provoked by its interaction with BSA. The complex BSA:CR displays a strong ICD spectrum with a positive band at 412nm and two negative bands at 356 and 490nm. The use of site I and site II albumin ligands as warfarin and ibuprofen, respectively, provoked different alterations in the Congo red ICD spectrum. The BSA binding sites were modified by oxidation and the ICD signal was sensitive to this alteration. The thermal treatment of the BSA:CR complex (30-90°C) was monitored by ICD at 490nm and showed a sigmoidal pattern typical of phase transition in proteins. The altered ICD spectrum is consistent with the formation of amyloid-like fibril aggregates in BSA, which was confirmed by thioflavin T and Rayleigh scattering assays. In conclusion, the ICD provoked by the binding of Congo red to albumin may represent a new spectroscopic technique for studying alterations in the structure of albumin regarding its binding sites and the formation of amyloid aggregates.en
dc.description.affiliationUnespUniversidade Estadual Paulista, Departamento de Química, Faculdade de Ciências de Bauru
dc.description.sponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.description.sponsorshipConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.description.sponsorshipIdFAPESP: 2013/08784-0
dc.identifier.citationSpectrochimica Acta. Part A, Molecular And Biomolecular Spectroscopy, v. 150, p. 321-330, 2015.
dc.publisherElsevier B. V.
dc.relation.ispartofSpectrochimica Acta. Part A, Molecular And Biomolecular Spectroscopy
dc.rights.accessRightsAcesso restrito
dc.subjectAmyloid aggregatesen
dc.subjectBinding sitesen
dc.subjectCongo reden
dc.subjectInduced circular dichroismen
dc.titleAlbumin-induced circular dichroism in Congo red: applications for studies of amyloid-like fibril aggregates and binding sitesen
dcterms.rightsHolderElsevier B. V.
unesp.campusUniversidade Estadual Paulista (Unesp), Faculdade de Ciências, Baurupt