title: Spectrofluorimetric study of the interaction of methyl-parathion with fish serum albumin.
abstract: The interaction of methyl-parathion with the albumin of Piaractus mesopotamicus (Holmberg 1887) (= pacu), a fish species typical of Brazilian rivers, was studied and the results compared with known values for human and bovine albumin obtained in an earlier investigation. Methyl-parathion (O,O-dimethyl O-p-nitrophenyl phosphorothioate) is an organophosphorous pesticide still used in agriculture and fish farming in many countries. The fluorescence quenching technique with tryptophan as a natural probe was used to detect for the presence of methyl-parathion. Fluorescence can be mathematically expressed by the Stern-Volmer equation to calculate quenching constants, and changes in the behavior of Stern-Volmer curves at different temperatures indicate the nature of the mechanism causing the quenching. Our results indicate that methyl-parathion forms a complex with fish albumin. The estimated association constant is 9.73 x 103 (+/- 4.9 x 102) M(-1) at 25 degrees C.
authors.affiliation: Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil. dilsons@uerj.br.
authors.forename: Dilson
authors.initials: D
authors.lastname: Silva
authors.affiliation: Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil.
authors.forename: Madelayne
authors.initials: M
authors.lastname: Cortez-Moreira
authors.affiliation: Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil.
authors.forename: Vera Lúcia Freire
authors.initials: VLF
authors.lastname: Cunha Bastos
authors.affiliation: Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil.
authors.forename: Jayme
authors.initials: J
authors.lastname: Cunha Bastos
authors.affiliation: Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil.
authors.forename: Célia
authors.initials: C
authors.lastname: Martins Cortez
mesh_terms: D000818:Animals; D002417:Cattle; D005399:Fishes / Q000378:metabolism*; D005453:Fluorescence; D006801:Humans; D007306:Insecticides / Q000378:metabolism*; D008743:Methyl Parathion / Q000378:metabolism*; D008954:Models, Biological; D012709:Serum Albumin / Q000378:metabolism*; D013045:Species Specificity; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D014364:Tryptophan
chemical_list: D007306:Insecticides; D012709:Serum Albumin; D008743:Methyl Parathion; D014364:Tryptophan