Saldaña A, Sousa O E, Orn A, Harris R A
Center for Research and Diagnosis of Parasitic Diseases (CIDEP), Faculty of Medicine, University of Panama.
Acta Trop. 1998 Jun 15;70(1):87-99. doi: 10.1016/s0001-706x(98)00020-5.
The epimastigote stage of Trypanosoma rangeli release a sialidase with a high sialic acid hydrolysis capacity. We demonstrate that sialidase secretion is an active process that is reduced at low temperatures and in the presence of sodium azide. The enzyme is continuously released until certain maximally active concentrations are attained in the BHI culture medium when the parasite density reaches 2-3 x 10(6) cells. When introduced into culture medium already containing such enzyme levels, freshly harvested parasites do not secrete additional sialidase. These findings suggest a self-regulating mechanism and a biological role for the secreted T. rangeli sialidase. The secreted enzyme was purified to homogeneity by fractionation with ammonium sulphate and affinity chromatography. Antibodies raised against the purified molecule recognized antigens of similar molecular weights (73 kDa) in western immunoblotting analyses of T. rangeli and T. cruzi whole cell lysates. No antigenic recognition was recorded against T. cruzi active sialidase/trans-sialidase polypeptides or Clostridium perfringens and Vibrio cholerae commercial sialidases. These observations may indicate the expression of different antigenic domains in T. rangeli, T. cruzi and bacterial sialidases.
兰氏锥虫的上鞭毛体阶段释放出一种具有高唾液酸水解能力的唾液酸酶。我们证明唾液酸酶的分泌是一个活跃过程，在低温和叠氮化钠存在的情况下会减少。当寄生虫密度达到2 - 3×10⁶个细胞时，该酶会持续释放，直到在BHI培养基中达到某些最大活性浓度。当将新鲜收获的寄生虫引入已经含有这种酶水平的培养基中时，它们不会分泌额外的唾液酸酶。这些发现提示了兰氏锥虫分泌的唾液酸酶存在一种自我调节机制和生物学作用。通过硫酸铵分级分离和亲和层析将分泌的酶纯化至同质。在对兰氏锥虫和克氏锥虫全细胞裂解物的western免疫印迹分析中，针对纯化分子产生的抗体识别出分子量相似（73 kDa）的抗原。未记录到针对克氏锥虫活性唾液酸酶/转唾液酸酶多肽或产气荚膜梭菌和霍乱弧菌商业唾液酸酶的抗原识别。这些观察结果可能表明兰氏锥虫、克氏锥虫和细菌唾液酸酶中不同抗原结构域的表达。
