el Meanawy M A, Aji T, Phillips N F, Davis R E, Salata R A, Malhotra I, McClain D, Aikawa M, Davis A H
Case Western Reserve University, Cleveland, Ohio.
Am J Trop Med Hyg. 1990 Jul;43(1):67-78. doi: 10.4269/ajtmh.1990.43.67.
Schistosoma mansoni uses a variety of proteases termed hemoglobinases to obtain nutrition from host globin. Previous reports have characterized cDNAs encoding 1 of these enzymes. However, these sequences did not define the primary structures of the mRNA and protein. The complete sequence of the 1390 base mRNA has now been determined. It encodes a 50 kDa primary translation product. In vitro translations coupled with immunoprecipitations and Western blots of parasite lysates allowed visualization of the 50 kDa form. Production of the 31 kDa mature hemoglobinase from the 50 kDa species involves removal of both NH2 and COOH terminal residues from the primary translation product. Expression of hemoglobinase mRNA and protein was examined during larval parasite development. Low levels were observed in young schistosomula. After 6-9 days in culture, high hemoglobinase levels were seen which correlated with the onset of red blood cell feeding. Immunoelectron microscopy was employed to examine hemoglobinase location and function. In adult worms the enzyme was associated with the gut lumen and gut epithelium. In cercariae, the protease was observed in the head gland, suggesting new roles for the protease.
曼氏血吸虫利用多种被称为血红蛋白酶的蛋白酶从宿主球蛋白中获取营养。先前的报告已对编码其中一种酶的cDNA进行了表征。然而，这些序列并未确定mRNA和蛋白质的一级结构。现已确定了1390个碱基的mRNA的完整序列。它编码一种50 kDa的初级翻译产物。体外翻译结合免疫沉淀和寄生虫裂解物的蛋白质印迹可观察到50 kDa的形式。从50 kDa的物种产生31 kDa的成熟血红蛋白酶涉及从初级翻译产物中去除NH2和COOH末端残基。在幼虫寄生虫发育过程中检测了血红蛋白酶mRNA和蛋白质的表达。在年轻的血吸虫中观察到低水平。培养6 - 9天后，观察到高血红蛋白酶水平，这与开始摄取红细胞相关。采用免疫电子显微镜检查血红蛋白酶的定位和功能。在成虫中，该酶与肠腔和肠上皮相关。在尾蚴中，蛋白酶在头腺中被观察到，这表明该蛋白酶有新的作用。
