title: Separation, characterization, and specificity of alpha-mannosidases from Vigna umbellata.
abstract: Information about the specificity of glycosidase enzymes is important since it affects their use for characterization and synthesis of oligosaccharides. Two alpha-mannosidases (EC 3.2.1.24), I and II, were isolated from rice beans (Vigna umbellata). The native molecular weight of both isozymes was estimated to be 329,000, but pIs of form I were 5.03-5.34 and pIs of form II were 5.46-6.20. The two isozymes were characterized in terms of optimal pH and temperature, effects of metal ions, inhibition by swainsonine and 1-deoxymannojirimycin, and kinetic parameters 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 hydrolysis and synthesis, but their hydrolytic specificities towards Man alpha (1-3)[Man alpha (1-6)]Man were different.
authors.affiliation: Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Wongvithoonyaporn
authors.forename: C
authors.initials: C
authors.lastname: Bucke
authors.forename: J
authors.initials: J
authors.lastname: Svasti
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007887:Fabaceae / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008361:Mannosidases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D008670:Metals / Q000494:pharmacology; D008970:Molecular Weight; D010936:Plant Extracts / Q000032:analysis; D010940:Plant Proteins / Q000032:analysis / Q000302:isolation & purification; D010946:Plants, Medicinal; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008670:Metals; D010936:Plant Extracts; D010940:Plant Proteins; D008361:Mannosidases