title: Chemical changes in bovine serum albumin photoinduced by pterin.
abstract: The exposure to UV-A radiation of bovine serum albumin (BSA) in aerated aqueous solution in the presence of pterin (Ptr), results in chemical and conformational modifications of the protein. Ptr belongs to a family of heterocyclic compounds that are well-known type I (electron-transfer) and type II (singlet oxygen) photosensitizers. The evolution of the photosensitized processes was followed by UV/vis spectrophotometry and fluorescence spectroscopy indicating that tryptophan (Trp) and tyrosine (Tyr) residues were affected. Additionally, conformational changes were evaluated by electrophoresis (SDS-PAGE) and size exclusion chromatography coupled with dynamic light scattering detection, showing that BSA undergoes dimerization, via the formation of Tyr radicals. The degradation of Trp residues takes place faster than the oligomerization of the protein. The photosensitized process is initiated by an electron transfer from BSA to the triplet excited stated of Ptr, being a purely dynamic mechanism.
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, 1900 La Plata, Argentina.
authors.forename: Andrés H
authors.initials: AH
authors.lastname: Thomas
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, 1900 La Plata, Argentina.
authors.forename: Beatriz N
authors.initials: BN
authors.lastname: Zurbano
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, 1900 La Plata, Argentina.
authors.forename: Carolina
authors.initials: C
authors.lastname: Lorente
authors.affiliation: Instituto de Química y Físico-Químicas Biológicas (IQUIFIB), Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires, Argentina.
authors.forename: Javier
authors.initials: J
authors.lastname: Santos
authors.affiliation: Instituto de Química y Físico-Químicas Biológicas (IQUIFIB), Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires, Argentina.
authors.forename: Ernesto A
authors.initials: EA
authors.lastname: Roman
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, 1900 La Plata, Argentina. Electronic address: ldantola@inifta.unlp.edu.ar.
authors.forename: M
authors.initials: M
authors.lastname: Laura Dántola
mesh_terms: D000818:Animals; D002417:Cattle; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D005609:Free Radicals / Q000737:chemistry; D011622:Pterins / Q000737:chemistry* / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: D005609:Free Radicals; D011622:Pterins; C408694:tyrosine radical; D012710:Serum Albumin, Bovine; D014443:Tyrosine; D014364:Tryptophan