Beta-cyclodextrin glucosyl tranferase enzyme mutant for producing gamma-cyclodextrin and use thereof

The present invention discloses a production γ- cyclodextrin β- cyclodextrin glycosyltransferase mutants and their use, which amino acid sequence SEQIDNO: 1, the mutant enzymes relative to the non-mutated β- ring dextrin glycosyltransferase γ- cyclodextrin having a high functionality, have widespread use in the production of starch-γ- cyclodextrin.