Bughio N I, Faubert G M, Prichard R K
Institute of Parasitology, McGill University, Ste-Anne de Bellevue, Quebec, Canada.
J Parasitol. 1994 Feb;80(1):126-32.
The binding of tritiated mebendazole, a benzimidazole anthelmintic, to tubulin derived from intestine, body wall muscle, and reproductive system of adult Ascaris suum was examined and compared. Mebendazole binding was resolved into specific and nonspecific binding and the binding affinity (Ka) and maximum binding at infinite ligand concentration (Bmax) determined. Electron microscopy was performed to assess the tubulin in various tissues of A. suum quantitatively by observing the presence of microtubules. Total binding was highest in intestine followed by body wall muscle. It was least in the reproductive system. The intestine demonstrated greater specific binding per milligram of protein than the body wall muscle. However, in the reproductive system extract, high affinity binding was not detected. After correction for nonspecific binding of ligand, the results indicated that the Bmax of mebendazole for the tubulin of A. suum intestine was about 3-fold higher than for that of body wall muscle. The Ka of mebendazole for intestinal tubulin was similar to that for body wall muscle. Electron microscopy of A. suum tissues demonstrated that the tubulin content decreased from the intestine through the body wall muscle to the reproductive system. Differences in tubulin content from different tissues may determine the selective sensitivity of these tissues to benzimidazole attack.
研究并比较了氚标记的甲苯咪唑（一种苯并咪唑驱虫药）与源自猪蛔虫成虫肠道、体壁肌肉和生殖系统的微管蛋白的结合情况。甲苯咪唑结合被解析为特异性结合和非特异性结合，并测定了结合亲和力（Ka）和无限配体浓度下的最大结合量（Bmax）。通过观察微管的存在，进行电子显微镜检查以定量评估猪蛔虫各种组织中的微管蛋白。总结合量在肠道中最高，其次是体壁肌肉，在生殖系统中最少。每毫克蛋白质中，肠道显示出比体壁肌肉更高的特异性结合。然而，在生殖系统提取物中未检测到高亲和力结合。校正配体的非特异性结合后，结果表明甲苯咪唑对猪蛔虫肠道微管蛋白的Bmax比对体壁肌肉微管蛋白的Bmax高约3倍。甲苯咪唑对肠道微管蛋白的Ka与对体壁肌肉微管蛋白的Ka相似。猪蛔虫组织的电子显微镜检查表明，微管蛋白含量从肠道经体壁肌肉到生殖系统逐渐降低。不同组织中微管蛋白含量的差异可能决定了这些组织对苯并咪唑攻击的选择性敏感性。
