Britain Purification and Properties of a - D - Mannosidase from Jack - Bean Meal

1. c-Mannosidase from jack-bean meal was pturified 150-fold. fl-N-Acetylglucosaminidase and f-galactosidase were removed from the preparation by treatment with pyridine. Zn2+ was added during the purification to stabilize the cxmannosidase. 2. At pH values below neutrality, x-mannosidase undergoes reversible spontaneous inactivation at a rate dependent on the temperature, the degree of dilution and the extent of purification. The enzyme is also subject to irreversible inactivation, which is prevented by the addition of albumin. 3. Reversible inactivation of ae-mannosidase is accelerated by EDTA and reversed or prevented by Zn2+. Other cations, such as Co2+, Cd2+ and Cu2+, accelerate inactivation; an excess of Zn2+ again exerts a protective action, and so does EDTA in suitable concentration. 4. Neither Zn2+ nor EDTA has any marked effect in the assay of untreated enzyme. In an EDTA-treated preparation, however, Zn2+ reactivates the enzyme during assay. 5. It is postulated that ax-mannosidase is a dissociable Zn2+-protein complex in which Zn2+ is essential for enzyme activity.