Activation of acetylcholinesterase by monovalent (Na+,K+) and divalent (Ca2+,Mg2+) cations.

The activation of acetylcholinesterase [EC 3.1.1.7 (AChE)] by monovalent and divalent metal ions has been investigated by kinetic experiments under steady-state conditions (pH-stat method). It has been shown that at low ionic strength the enhancement of the activity by both monovalent and divalent metal ions can be explained as an electrostatic effect. Thereby, enhancement of the concentration of monovalent metal ions (Na+ and K+) acts by reducing the penetration depth of the electric field of carboxylate groups located at the active center whereby divalent metal ions (Ca2+ and Mg2+) act by a complex formation with these charged groups.