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Characterization of jack-bean alpha-D-mannosidase as a zinc metalloenzyme.

ABSTRACT: 1. Two methods were used to obtain alpha-mannosidase free from unbound Zn2+, (a) by removal of excess of metal ion from preparations purified in the presence of Zn2+ and (b) by purification under conditions that eliminate the need to add Zn2+. 2. The purified enzyme is homogeneous on ultracentrifugation, polyacrylamide-gel electrophoresis and gel chromatography. 3. The molecular weight is estimated to be 230 000. 4. The enzyme contains between 470 and 565 mug of zinc/g of protein, corresponding to between 1.7 and 2 atoms of zinc/enzyme molecule. The contents of other metals are much lower. 5. The enzyme is inactivated by chelating agents and activity is restored by Zn2+. 6. No other metal ion was found to replace Zn2+ with retention of activity. Some bivalent metal ions, e.g. Cu2+, rapidly inactivate the enzyme. 7. The results indicate that jack-bean alpha-mannosidase exists naturally as a zinc-protein complex and may be considered as a metalloenzyme.

SUBMITTER: Snaith SM

PROVIDER: S-EPMC1165377 | biostudies-other | 1975 Apr

REPOSITORIES: biostudies-other

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Purification and properties of alpha-D-mannosidase from jack-bean meal.

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Jack bean urease imaged at 39kX nominal magnification

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Jack bean urease imaged at 63kX nominal magnification

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Jack bean urease imaged at 79kX nominal magnification

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