Purification and characterization of a novel fungal alpha-glucosidase from Mortierella alliacea with high starch-hydrolytic activity

Biosci Biotechnol Biochem. 2002 Nov;66(11):2415-23. doi: 10.1271/bbb.66.2415.


The fungal strain Mortierella alliacea YN-15 is an arachidonic acid producer that assimilates soluble starch despite having undetectable alpha-amylase activity. Here, a alpha-glucosidase responsible for the starch hydrolysis was purified from the culture broth through four-step column chromatography. Maltose and other oligosaccharides were less preferentially hydrolyzed and were used as a glucosyl donor for transglucosylation by the enzyme, demonstrating distinct substrate specificity as a fungal alpha-glucosidase. The purified enzyme consisted of two heterosubunits of 61 and 31 kDa that were not linked by a covalent bond but stably aggregated to each other even at a high salt concentration (0.5 M), and behaved like a single 92-kDa component in gel-filtration chromatography. The hydrolytic activity on maltose reached a maximum at 55 degrees C and in a pH range of 5.0-6.0, and in the presence of ethanol, the transglucosylation reaction to form ethyl-alpha-D-glucoside was optimal at pH 5.0 and a temperature range of 45-50 degrees C.

MeSH terms

  • Binding Sites
  • Catalysis
  • Chromatography, Liquid / methods
  • Electrophoresis, Polyacrylamide Gel / methods
  • Enzyme Stability
  • Glucose / analysis
  • Glucose / biosynthesis
  • Glycosylation
  • Hydrogen-Ion Concentration
  • Hydrolysis
  • Maltose / metabolism
  • Mortierella / classification
  • Mortierella / enzymology*
  • Protein Subunits / chemistry
  • Starch / metabolism*
  • Substrate Specificity
  • Temperature
  • alpha-Glucosidases / chemistry
  • alpha-Glucosidases / isolation & purification*
  • alpha-Glucosidases / metabolism*


  • Protein Subunits
  • Maltose
  • Starch
  • alpha-Glucosidases
  • Glucose