Effect of ions on the activity of brain acetylcholinesterase from tropical fish

• Published in: Journal of coastal life medicine Vol. 3; no. 7; pp. 505 - 514
• Main Authors: Assis, Caio Rodrigo Dias, Linhares, Amanda Guedes, Oliveira, Vagne Melo, Franca, Renata Cristina Penha, Santos, Juliana Ferreira, Carvalho, Elba Veronica Matoso Maciel, Bezerra, Ranilson Souza, Carvalho, Luiz Bezerra
• Format: Journal Article
• Language: English
• Published: 01.07.2015
• Subjects: Arapaima gigas; Brackish; Colossoma macropomum; Electrophorus; Oreochromis niloticus; Rachycentron
• ISSN: 2309-5288; 2309-6152
• DOI: 10.12980/JCLM.3.2015J5-11

Objective: To investigate the effect of ions on brain acetylcholinesterase (AChE; EC 3.1.1.7) activities from economic important fish [pirarucu, Arapaima gigas; tambaqui, Colossoma macropomum; cobia, Rachycentron canadum(R. canadum) and Nile tilapia, Oreochromis niloticus(O. niloticus)] comparing with a commercial enzyme from electric eel [Electrophorus electricus(E. electricus)]. Methods: The in vitro exposure was performed at concentrations ranging from 0.001 to 10 mmol/L (except for ethylene diamine tetraacetic acid; up to 150 mmol/L). Inhibition kinetics on R. canadum and O. niloticus were also observed through four methods (Michaelis-Menten, Lineweaver-Burk, Dixon and Cornish-Bowden plots) in order to investigate the type of inhibition produced by some ions. Results: Hg super(2+), As super(3+), Cu super(2+), Zn super(2+), Cd super(2+) caused inhibition in all the species under study. Ca super(2+), Mg super(2+) and Mn super(2+) induced slight activation in R. canadum enzyme while Pb super(2+), Ba super(2+), Fe super(2+), Li super(+) inhibited the AChE from some of the analyzed species. The lowest IC sub(50) and Ki values were estimated for E. electricus AChE in presence of Hg super(2+), Pb super(2+), Zn super(2+). Under our experimental conditions, the results for R. canadum and O. niloticus, As super(3+), Cu super(2+), Cd super(2+), Pb super(2+) and Zn super(2+) showed a noncompetitive/mixed-type inhibition, while Hg super(2+) inhibited the enzyme in a mixed/competitivelike manner. Conclusions: E. electricus AChE activity was affected by ten of fifteen ions under study showing that this enzyme could undergo interference by these ions when used as pesticide biosensor in environmental analysis. This hindrance would be less relevant for the crude extracts.