Mohammed S R, Faubert G M
Institute of Parasitology of McGill University, Québec, Canada.
Parasite. 1995 Mar;2(1):31-9. doi: 10.1051/parasite/1995021031.
The effects on disaccharidase activities of challenging gerbils previously exposed to Giardia lamblia with fradions of the crude trophozoite extract were examined. Gel filtration of the soluble extract on a Sephacryl S-200 HR column resulted in 3 fradions: F1, F2 and F3. Only a challenge with fraction F1 (0.1 mg total dose) was found to induce disaccharidase deficiencies. Boiling F1 prior to challenge did not change this effect on the enzyme activities. However, the decreases were not obtained when the total F1 dose was reduced to 0.05 mg. Column chromatography of fraction F1 under dissociating and reducing conditions resulted in 2 further fractions: F1a and F1b. Challenging immune gerbils with F1b led to impairments of disaccharidose activity similar to those obtained with F1. Protein analysis of the crude extract, as well as the fractions of the extract, revealed several high and low molecular weight bonds. These findings indicate that a constituent(s) of fraction F1b is the portion of the parasite which induces disaccharidase deficiencies in immune gerbils. This fraction consists of proteins ranging in molecular weight from 32 to 200 kDa. In addition the G. lamblia fraction involved in the decreases in enzyme activity is heat-stable.
研究了用粗滋养体提取物的级分攻击先前暴露于蓝氏贾第鞭毛虫的沙鼠对双糖酶活性的影响。将可溶性提取物在Sephacryl S - 200 HR柱上进行凝胶过滤，得到3个级分：F1、F2和F3。仅发现用F1级分（总剂量0.1 mg）攻击会诱导双糖酶缺乏。攻击前将F1煮沸不会改变对酶活性的这种影响。然而，当F1总剂量降至0.05 mg时，未出现酶活性降低。在解离和还原条件下对F1级分进行柱色谱分离，得到另外2个级分：F1a和F1b。用F1b攻击免疫沙鼠导致双糖酶活性受损，与用F1攻击时相似。对粗提取物及其级分进行蛋白质分析，发现了几个高分子量和低分子量条带。这些发现表明，F1b级分中的一种成分是寄生虫中诱导免疫沙鼠双糖酶缺乏的部分。该级分由分子量在32至200 kDa之间的蛋白质组成。此外，参与酶活性降低的蓝氏贾第鞭毛虫级分是热稳定的。
