Biomedical Studies on Sialidase and Beta-Galactosidase

从人胎盘中高纯度纯化唾液酸酶（J. Biochem.）。， 103, 86-90, 1988)。在sds -聚丙烯酰胺凝胶电泳上，纯化酶得到了分子量为78K、64K、46K、30K和20K的5条蛋白带。为了研究唾液酸酶中30K和20K蛋白组分的功能，用30K和20K蛋白制备兔抗血清。另一方面，从牛脑纯化的β -半乳糖苷酶多聚体中也分离到了32K和20K蛋白（J. Biochem.）。肝脏（日本J. Exp. Med. 58,129 - 139,1988）。抗30K和32K蛋白抗血清对唾液酸酶和-半乳糖苷酶的影响表明，30K和32K蛋白对-半乳糖苷酶和-唾液酸苷酶活性的影响几乎相同。研究了半乳糖sididosis患者尸检肝脏中的β -半乳糖苷酶。患者肝脏糖蛋白部分的β -半乳糖苷酶活性为控制值的7.3%，而患者肝脏中的唾液酸酶活性未检测到。-半乳糖苷酶的多样性和免疫印迹分析表明，患者肝脏中残留的-半乳糖苷酶能够形成-半乳糖苷酶多聚体，30K蛋白可能有助于-半乳糖苷酶的聚集。研究了唾液酸酯酶的活化机制。我们发现唾液酸酶的激活是由蛋白酶功能引起的。

A sialidase was highly purified from human placenta (J. Biochem., 103, 86-90, 1988). On SDS-polyacrylamide gel electrophoresis, the purified enzyme gave five protein bands with molecular weights of 78K, 64K, 46K, 30K and 20K. To investigate the function of 30K and 20K protein components in the sialidase, rabbit antisera were raised against 30K and 20K proteins. On the other hand, 32K and 20K proteins were also isolated from beta-galactosidase multimer purified from bovine brain (J. Biochem., 100, 707-715, 1986) and liver (Japan J. Exp. Med., 58, 129-139, 1988). The effects of anti 30K and 32K proteins antisera on sialidase or beta-galactosidase showed that 30K and 32K proteins were almost same and contributed to not only beta-galactosidase but also sialidase activities.beta-Galactosidase in the autopsy liver of a patient with galactosialidosis was studied. Beta-Galactosidase activity in the glycoprotein fraction from the patient liver was 7.3% of the control value, while sialidase activity in the patient liver was undetectable. The multiplicity of the beta-galactosidase and immunoblotting analysis show that the residual beta-galactosidase in the patient liver is capable of formation of beta-galactosidase multimer and the 30K protein may contribute to the aggregation of beta-galactosidase.Activation mechanism of sialidase was studied. We found that the activation of sialidase was caused by protease function.