title: An arsenic fluorescent compound as a novel probe to study arsenic-binding proteins.
abstract: Arsenic-binding proteins are under continuous research. Their identification and the elucidation of arsenic/protein interaction mechanisms are important because the biological effects of these complexes may be related not only to arsenic but also to the arsenic/protein structure. Although many proteins bearing a CXXC motif have been found to bind arsenic in vivo, new tools are necessary to identify new arsenic targets and allow research on protein/arsenic complexes. In this work, we analyzed the performance of the fluorescent compound APAO-FITC (synthesized from p-aminophenylarsenoxide, APAO, and fluorescein isothiocyanate, FITC) in arsenic/protein binding assays using thioredoxin 1 (Trx) as an arsenic-binding protein model. The Trx-APAO-FITC complex was studied through different spectroscopic techniques involving UV-Vis, fluorescence, atomic absorption, infrared and circular dichroism. Our results show that APAO-FITC binds efficiently and specifically to the Trx binding site, labeling the protein fluorescently, without altering its structure and activity. In summary, we were able to study a protein/arsenic complex model, using APAO-FITC as a labeling probe. The use of APAO-FITC in the identification of different protein and cell targets, as well as in in vivo biodistribution studies, conformational studies of arsenic-binding proteins, and studies for the design of drug delivery systems for arsenic anti-cancer therapies, is highly promising.
authors.affiliation: Laboratorio de Biomembranas, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Buenos Aires, Argentina.
authors.forename: A Lis
authors.initials: AL
authors.lastname: Femia
authors.forename: C Facundo
authors.initials: CF
authors.lastname: Temprana
authors.forename: Javier
authors.initials: J
authors.lastname: Santos
authors.forename: María Laura
authors.initials: ML
authors.lastname: Carbajal
authors.forename: María Silvia
authors.initials: MS
authors.lastname: Amor
authors.forename: Mariano
authors.initials: M
authors.lastname: Grasselli
authors.forename: Silvia Del V
authors.initials: Sdel V
authors.lastname: Alonso
mesh_terms: D001151:Arsenic / Q000737:chemistry* / Q000378:metabolism; D001152:Arsenicals / Q000737:chemistry* / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D058767:Protein Unfolding; D013057:Spectrum Analysis; D013696:Temperature; D013879:Thioredoxins / Q000737:chemistry / Q000378:metabolism
chemical_list: D001152:Arsenicals; D002352:Carrier Proteins; D005456:Fluorescent Dyes; C530734:p-aminophenylarsine oxide; D013879:Thioredoxins; D016650:Fluorescein-5-isothiocyanate; D001151:Arsenic