Electric-field induced effects in acetylcholinesterase.
Acetylcholinesterase from Torpedo marmorata Risso was adsorbed as a monolayer on to a germanium internal reflection plate. The behaviour of the enzyme in strong electric fields was investigated by means of infrared attenuated total reflection (ATR) spectroscopy. A positive potential on the germanium plate was found to result in an electric-field induced dissociation of the -COOH groups of Asp and Glu residues. Independently, a field-induced conformational change of the protein was observed. Since a negative charge on the enzyme facilitates the trapping of positively charged acetylcholine, and this negative charge can be controlled via the potential of the support to which it is adsorbed, a new electrostatic regulation model for acetylcholinesterase activity in excitable membranes is proposed.
Fringeli
U P
UP
Laboratory for Physical Chemistry Swiss Federal Institute of Technology CH-8092 Zurich, Switzerland.
Hofer
P
P