Purification and biochemical characterization of acetylcholinesterase (AChE) from the excretory/secretory products of<i>Trichostrongylus colubriformis</i>

Abstract

Acetylcholinesterase (AChE) has been purified from the excretory/secretory (ES) products of Trichostrongylus colubriformis (using edrophonium chloride linked to epoxy-activated Sepharose) with yields of 40-50%. Purity was confirmed by polyacrylamide gel electrophoresis (using silver [protein] and Karnovsky [activity] stains) and measurement of specific AChE activity. Further analysis of the purified fractions by gel filtration and sucrose density gradient techniques revealed the existence of 2 forms of hydrophilic AChE (M(r) 189 and 80 kDa). From the data we deduce these to be the globular monomer and dimer, G1 and G2 forms of AChE. Inhibition studies using BW284C51, iso-OMPA and excess substrate, along with substrate specificity studies, show both forms to be true acetylcholinesterases. We are currently assessing the protective immunogenicity of purified AChE in sheep.