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Pure Appl. Chem., 2007, Vol. 79, No. 12, pp. 2339-2349

Screening of acetylcholinesterase inhibitors in snake venom by electrospray mass spectrometry*

André Liesener1, Anna-Maria Perchuc2, Reto Schöni2, Nils Helge Schebb3, Marianne Wilmer2 and Uwe Karst1,3

1 University of Twente, Chemical Analysis Group and MESA+ Institute for Nanotechnology, P.O. Box 217, 7500 AE Enschede, The Netherlands
2 Pentapharm Ltd., Engelgasse 109, 4002 Basel, Switzerland
3 Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstrasse 30, 48149 Münster, Germany

Abstract: An electrospray ionization/mass spectrometry (ESI/MS)-based assay for the determination of acetylcholinesterase (AChE)-inhibiting activity in snake venom was developed. It allows the direct monitoring of the natural AChE substrate acetylcholine (AC) and the respective product choline. The assay scheme was employed in the screening for neurotoxic activity in fractions of the venom of Bothrops moojeni. AChE inhibition was assessed in two fractions. As a positive control, the established AChE inhibitor 1,5-bis(4-allyl-dimethylammoniumphenyl)pentan-3-one dibromide (BW284c51) was used, a dose-response curve for this compound was generated and the IC50 value for the inhibitor was determined to be 1.60 ± 0.09 × 10-9 mol L-1. The dose-response curve was used as "calibration function" for the venom inhibition activity, resulting in BW284c51-equivalent concentrations of 1.76 × 10-9 mol L-1 and 1.07 × 10-9 mol L-1 for the two fractions containing activity. The ESI/MS-based assay scheme was validated using the established Ellman reaction. The data obtained using both methods were found to be in good agreement. The ESI/MS-based assay scheme is therefore an attractive alternative to the standard colorimetric assay.
*Invited contribution to a collection of papers for the IUPAC project 2005-042-1-300 "Chemistry for Biology". Other contributions to the project are published in this issue, pp. 2179-2366.