SEPARATION, CHARACTERIZATION, AND SPECIFICITY OF ALPHA-MANNOSIDASES FROM VIGNA-UMBELLATA

Information about the specificity of glycosidase enzymes is important since it affects their use for characterization and synthesis of oligo saccharides. Two alpha-mannosidases (EC 3.2.1.24), I and II, were isol ated from rice beans (Vigna umbellata). The native molecular weight of both isozymes was estimated to be 329,000, but pls of form I were 5.0 3-5.34 and pls of form II were 5.46-6.20. The two isozymes were charac terized in terms of optimal pH and temperature, effects of metal ions, inhibition by swainsonine and 1-deoxymannojirimycin, and kinetic para meters for p-nitrophenyl-alpha-D-mannopyranoside and Man alpha(1-2)Man . Both enzymes were more specific towards Man alpha(1-2)Man in both hy drolysis and synthesis, but their hydrolytic specificities towards Man alpha(1-3)[Man alpha(1-6)]Man were different.