González-Páez Gonzalo Ernesto, Argüello-García Raúl, Alba-Hurtado Fernando
Department of Biological Science and Postgraduate Program on Microbiology, Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de México, 54700 Mexico City, Mexico.
Vet Parasitol. 2007 Jul 20;147(3-4):332-5. doi: 10.1016/j.vetpar.2007.03.036. Epub 2007 May 22.
Developing larvae of Toxocara canis may secrete several kinds of enzymes within the egg perivitelline fluid (EPF) prior to and during hatching. In particular, proteinases in EPF could play a role in larval emergence within the host gastrointestinal lumen but its presence and nature is unknown. In this work, proteolytic activities in hatching fluid of T. canis were identified and analysed by substrate gel electrophoresis at different pH values and by using type specific protease inhibitors. Three bands of 91, 68 and 38 kDa showed gelatinolytic activity and all proteinase activity from EPF was of the aspartic-type since it was inhibited by pepstatin A. Interestingly, a significantly higher proteolytic activity was observed at acidic pH (< or =5.5). These data suggest that T. canis developmentally secretes and accumulates in EPF aspartic proteinases with a pH-dependent activity that might help the parasite to take advantage of conditions in the host gastrointestinal microenvironment where egg hatching is induced and executed.
犬弓首蛔虫发育中的幼虫在孵化前及孵化期间可能会在卵黄膜液（EPF）中分泌多种酶。特别是，EPF中的蛋白酶可能在幼虫在宿主胃肠道腔内的孵出过程中发挥作用，但其存在情况和性质尚不清楚。在这项研究中，通过在不同pH值下进行底物凝胶电泳并使用类型特异性蛋白酶抑制剂，对犬弓首蛔虫孵化液中的蛋白水解活性进行了鉴定和分析。91、68和38 kDa的三条带显示出明胶水解活性，并且EPF中的所有蛋白酶活性均为天冬氨酸型，因为它被胃蛋白酶抑制剂A抑制。有趣的是，在酸性pH（≤5.5）下观察到明显更高的蛋白水解活性。这些数据表明，犬弓首蛔虫在发育过程中在EPF中分泌并积累具有pH依赖性活性的天冬氨酸蛋白酶，这可能有助于寄生虫利用诱导和执行卵孵化的宿主胃肠道微环境中的条件。
