The interaction of methyl-parathion with serum and albumin of the neo-tropical fish Piaractus mesopotamicus.
The interaction of methyl-parathion with serum and albumin of pacu, Piaractus mesopotamicus, was studied, using the fluorescence quenching technique. Pacu is a neo-tropical fish specie inhabitant of rivers from western regions of Brazil. Methyl-parathion (O,O-dimethyl O-p-nitrophenyl phosphorothioate) is an organophosphorous pesticide still used in agriculture and fish farming in many countries. The quenching of fluorescence can be mathematically expressed by the Stern-Volmer equation to calculate quenching constants. Stern-Volmer curves analysis is able to give important information about the pesticide-albumin interaction. Our results showed that the serum quenching reached 10% when the molar ratio of pesticide/albumin was about 7:1 for the three temperatures of the experiment. For the pure albumin quenching of 10%, methyl-parathion concentrations were 6, 7 and 9 times higher than albumin at 20, 25 and 30 degrees C, respectively. The calculated Stern-Volmer constants at 25 degrees C were 9.73x10(3)(+/-4.9x10(2))M(-1) for serum and 9.20x10(3)(+/-2.0x10(2))M(-1) for albumin. It was observed that albumin quenching is the phenomenon contributing to the quenching of the pacu serum fluorescence for methyl-parathion concentration lower than 10microM, suggesting that the protein is the most important carrier for the pesticide in serum.
Department of Physiological Sciences, Rio de Janeiro State University, Rua: Prof. Manuel de Abreu, 444, 5 degrees andar, 20550-170 Rio de Janeiro, RJ, Brazil. dilsons@uerj.br
Dilson
D
Silva
Madelayne
M
Cortez-Moreira
Vera L F
VL
Cunha Bastos
Jayme
J
Cunha Bastos
Célia
C
Martins Cortez
D000818:Animals; D001798:Blood Proteins / Q000032:analysis; D005399:Fishes / Q000097:blood*; D005453:Fluorescence; D007306:Insecticides / Q000378:metabolism*; D008743:Methyl Parathion / Q000378:metabolism*; D011485:Protein Binding; D012709:Serum Albumin / Q000032:analysis / Q000378:metabolism*
D001798:Blood Proteins; D007306:Insecticides; D012709:Serum Albumin; D008743:Methyl Parathion