<span style="font-size:14.0pt;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";mso-ansi-language:EN-US;mso-fareast-language: EN-US;mso-bidi-language:AR-SA">Purification and characterization of a cholinesterase from <i>Haemonchus contortus</i></span>

192-197Acetylcho<span style="font-size:14.0pt; font-family:HiddenHorzOCR;mso-bidi-font-family:HiddenHorzOCR">linesterase (AChE) was purified from the extract of adult Haemonchus contortus &nbsp;by gel filtration, ion-exchange and ConA-Sepharose chromatography. The enzyme was also found to be secreted by the parasite during in vitro cultivation which was partially purified from the excretory-secretory products. Presence of enzyme specific antibodies were observed in animals having H. contortus infection. The molecular mass of the enzyme by SDS-PAGE was 144 kDa. The enzyme showed typical Michaelis-Menten kinetics at low substrate concentrations but was inhibited by substrate concentrations greater than 4 mM. The enzyme was stab le at 4°C for several weeks but lost 60% of the activity when heated to 60°C for 5 min. Physostigmine and neostigmine inhibited enzyme activity at low ( μM) concentrations whereas phenyl methyl sulfonyl fluoride (PMSF) and sodium fluoride (NaF) inhibited only at high concentrations (mM) . Significance of secreted AChE in host-parasite relationship is discussed.