ABSTRACT
Acetylcholinesterase (AChE) plays an important role in the therapy of Alzheimer's disease and in the detection of pesticides such as organophosphates which are also widely used in chemical warfare. The aim of this study is the physicochemical and kinetic characterization of brain and muscle ChE from Danio rerio (Zebrafish). Optimal activity was found for brain ChE at alkaline pHâ¯9.0 at 30⯰C, and for muscle ChE at alkaline pHâ¯8.5 at temperatures between 20⯰C and 35⯰C. The apparent kinetic constants, Kmapp and Vmaxapp, for brain ChE were determined as 0.191⯱â¯0.024â¯mM and 0.566⯱â¯0.028â¯U/mg protein, and for muscle ChE as 0.230⯱â¯0.030â¯mM and 0.677⯱â¯0.039â¯U/mg protein. Both brain and muscle ChE showed inhibition at high substrate concentrations. Brain and muscle ChE showed IC50 values for physostigmine of 0.61⯵M and 0.37⯵M, respectively. The ChE activity in brain was significantly inhibited by BW254c51 in all concentrations tested, but not by Iso-OMPA, while muscle ChE presented a moderate decrease (13 to 29%) in the activity values, indicating that BuChE is present.