Purification and characterization of a Bacillus sp. SAM1606 thermostable alpha-glucosidase with transglucosylation activity

Appl Microbiol Biotechnol. 1994 May;41(3):337-43. doi: 10.1007/BF00221229.

Abstract

We purified a novel alpha-glucosidase to homogeneity from an Escherichia coli recombinant transformed with the alpha-glucosidase gene from thermophilic Bacillus sp. SAM1606. The enzyme existed as mono- and multimeric forms of a promoter protein with a relative molecular weight of 64,000 and isoelectric point of 4.6. We isolated a monomeric form of the enzyme and characterized it. The enzyme was unique among the known alpha-glucosidases in both broad substrate specificity and high thermostability. The enzyme hydrolysed a variety of O-alpha-D-glucopyranosides such as nigerose, maltose, isomaltose, sucrose, and trehalose efficiently. The molecular activity (k0) and the Michaelis constant (Km) values at 55 degrees C and pH 6.0 for sucrose were 54.6 s-1 and 5.3 mM, respectively. The optimum pH and temperature for hydrolysis were pH 5.5 and 75 degrees C, respectively. The enzyme exhibited a high transglucosylation activity: it reacted with 1.8 M sucrose at 60 degrees C for 70 h to yield oligosaccharides containing theanderose in a maximum yield of 35% (w/w). High thermostability of the enzyme (stable up to 65 degrees C at pH 7.2 for 10 min) permits the transglucosylation reaction at high temperatures, which would be beneficial for continuous production of oligosaccharides from sucrose.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacillus / enzymology*
  • Catalysis
  • Cloning, Molecular
  • Enzyme Stability
  • Escherichia coli
  • Glucosidases / chemistry
  • Glucosidases / genetics
  • Glucosidases / isolation & purification
  • Glucosidases / metabolism*
  • Molecular Sequence Data
  • Substrate Specificity
  • Temperature

Substances

  • Glucosidases