| چکیده انگلیسی مقاله |
Background: Like several other parasites, Teladorsagia circumcincta secretes or excretes urea, but nei-ther the rate of efflux nor the possible metabolic sources of the urea has been considered. Methods: Parasites were maintained by passage through sheep. Urea efflux was measured using phe-nol/hypochlorite after treatment with urea aminohydrolase. The kinetics of creatine amidinohy-drolase and arginine amidinohydrolase were characterised by coupling the reactions with urea ami-nohydrolase and glutamate dehydrogenase. Results: Infective L 3 T. circumcincta secreted or excreted urea at 25% of the rate of NH 3 /NH 4+ . The rate of urea efflux was about 84 pmol h -1 (10 3 larvae) -1 over 4 hours, corresponding to about 11 nmol h -1 mg -1 protein. We could not detect urea aminohydrolase activity, but urea production by both creatine amidinohydrolase and arginine amidinohydrolase could be detected. The apparent K m and V max of creatine amidinohydrolase were 1.1 mM and 48 nmol h -1 mg -1 protein, respectively, and the activity was greatest at pH 8. The apparent K m and V max of arginine amidinohydrolase were 0.7 mM and 62 nmol h -1 mg -1 protein, respectively, and the activity was greatest at pH 7.9. Conclusion: The activity of creatine amidinohydrolase and arginine amidinohydrolase was sufficient to account for the rate of urea secretion or excretion. |
| نویسندگان مقاله |
n محمد | n muhamad
universiti kuala lumpur, royal college of medicine perak, 3 greentown road, 30450 ipoh, perak, malaysia.
lr والکر | lr walker
institute of food, nutrition and human health, massey university, private bag, palmerston north, new zealand.
dc simcock | dc simcock
institute of food, nutrition and human health, massey university, private bag, palmerston north, new zealand.
kc pedley | kc pedley
institute of food, nutrition and human health, massey university, private bag, palmerston north, new zealand.
hv simpson | hv simpson
institute of veterinary and biomedical sciences, massey university, private bag 11222, palmerston north, new zealand.
s brown | s brown
school of human life sciences, university of tasmania, locked bag 1320, launceston, tasmania 7250, australia.
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