| Research Abstract |
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.
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