Characterization of acid phosphatase and phosphorylcholine hydrolase in adult Haemonchus contortus.
An acid phosphatase (AP) and a phosphorylcholine hydrolase (PCH) were detected in excretory-secretory (ESP) products from adult Haemonchus contortus. The AP had a pH optimum of 4.5 and was inhibited by tartaric acid and sodium fluoride, but not by o-phenanthroline. The AP hydrolyzed paranitrophenol (pnp)-phosphate and to a lesser extent pnp-phenyl-phosphonate but did not hydrolyze diester substrates. Purified AP consisted of heterodimers with relative molecular weight (Mr) of 41.9 and 48.7 kDa and had a native molecular weight of 98 kDa by size-exclusion chromatography (SEC). The PCH had a pH optimum of about 9.5 and was inhibited by EDTA and o-phenanthroline but not by the specific phospholipase inhibitor D609. The specific activity of PCH in the ESP was approximately 25-fold less than that of AP. PCH also hydrolyzed 5'-thymidine monophosphate-pnp at a rate about 40% lower than pnp-phosphorylcholine but did not hydrolyze 3'-thymidine monophosphate-pnp. Partial purification of PCH suggests an Mr of 50.2 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and an Mr of 102 kDa by SEC. Both AP and PHC were secreted in vitro in a time-dependent manner and had their highest concentrations in the intestine. The results indicate that H. contortus adults secrete significant amounts of AP that might be a digestive enzyme. PCH is also an intestinal enzyme and is secreted in lesser amounts than AP. The PCH is probably not a phospholipase C but has some characteristics of a type I phosphodiesterase.
Fetterer
R H
RH
Parasite Biology and Epidemiology Laboratory, Livestock and Poultry Sciences Institute, Beltsville Agricultural Research Center, Maryland 20705, USA.
Rhoads
M L
ML
D000135:Acid Phosphatase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004492:Edetic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006189:Haemonchus / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D006868:Hydrolysis; D008970:Molecular Weight; D010618:Phenanthrolines / Q000494:pharmacology; D012756:Sheep; D012969:Sodium Fluoride / Q000494:pharmacology; D013644:Tartrates / Q000494:pharmacology; D014639:Vanadium / Q000494:pharmacology
D002800:Cholinesterase Inhibitors; D010618:Phenanthrolines; D013644:Tartrates; D014639:Vanadium; D012969:Sodium Fluoride; D004492:Edetic Acid; D006867:Hydrolases; C404902:phosphorylcholine hydrolase; D000135:Acid Phosphatase; C029768:tartaric acid; C025205:1,10-phenanthroline