Introducing transglycosylation activity in a liquefying alpha-amylase

By mutating Ala-289 by Phe or Tyr in the Bacillus stearothermophilus alpha- amylase, we induced this enzyme to perform alcoholytic reactions, a functio n not present in the wild-type enzyme. This residue was selected from homol og! analysis with neopullulanase. where the residue has been implicated in the control of transglycosylation [Kuriki et ai, (1996) J, Biol, Chem, 271, 17321-17329]. We made some inferences about the importance of electrostati c and geometrical modifications in the active site environment of the amyla se to explain the behavior of the modified enzyme. (C) 1999 Federation of E uropean Biochemical Societies.