Purification and characterization of a novel alpha-mannosidase from Aspergillus saitoi

J Biochem. 1986 Jun;99(6):1645-54. doi: 10.1093/oxfordjournals.jbchem.a135639.

Abstract

An alpha-mannosidase differing from 1,2-alpha-mannosidase was found to occur in Aspergillus saitoi. By a series of column chromatographies the enzyme was purified up to 1,000-fold, and its properties were studied in detail. The enzyme preparation, which was practically free from other exoglycosidases, showed a pH optimum of 5.0. In contrast to 1,2-alpha-mannosidase, the enzyme was strongly activated by Ca2+ ions. p-Nitrophenyl alpha-mannopyranoside was not hydrolyzed by the enzyme. Accordingly, the substrate specificity of the new alpha-mannosidase was studied by using a variety of tritium-labeled oligosaccharides. Studies with linear oligosaccharides revealed that the enzyme cleaves the Man alpha 1----3Man linkage more than 10 times faster than the Man alpha 1----6Man and the Man alpha 1----2Man linkages. Furthermore, it cleaves the Man alpha 1----6Man linkage of the Man alpha 1----6(Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4GlcNAcOT only after its Man alpha 1----3 residue is removed. Because of this specificity, the enzyme can be used as an effective reagent to discriminate R----Man alpha 1----6(Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4(+/- Fuc alpha 1----6)GlcNAcOT from its isomeric counterparts, Man alpha 1----6(R----Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4(+/- Fuc alpha 1----6)GlcNAcOT, in which R represents sugars.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aspergillus / enzymology*
  • Calcium / pharmacology
  • Chromatography / methods
  • Enzyme Activation / drug effects
  • Hydrolysis
  • Mannosidases / isolation & purification*
  • Mannosidases / metabolism
  • Oligosaccharides / metabolism
  • Substrate Specificity
  • alpha-Mannosidase

Substances

  • Oligosaccharides
  • Mannosidases
  • alpha-Mannosidase
  • Calcium