Purification and Properties of α-Mannosidase from Bakers' Yeast

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Abstract
The yeast α-mannosidase [EC 3.2.1.24] was purified 1160-fold from the crude extract of the autolysate. The purified preparation was practically free from α-glucosidase, β-glucosidase, α-galactosidase, β-galactosidase, β-mannosidase, and β-N-acetylhexosaminidase activities. After the separation of yeast mannan during the purification procedures the enzyme became unstable but could be stored at 5°C for three weeks with 50% loss of activity. The purified enzyme hydrolyzed both aryl and alkyl mannosides, but hydrolysis of yeast mannan proceeded slowly. Yeast mannan and Zn2+ increased the enzyme catalyzed hydrolysis of p-nitrophenyl mannoside, whereas NaN3 monoiodoacetate and methyl α-D-mannoside acted as inhibitors. The molecular weight was estimated to be 450,000 by gel filtration.