The invention belongs to the technical field of
gene engineering, and particularly relates to a beta-glycosidase SS-BGL
mutant for preparing rare ginsenosides and application of the beta-glycosidase SS-BGL
mutant. The beta-glycosidase SS-BGL
mutant is obtained by conducting single-site
mutation or double-site
mutation on beta-glycosidase SS-BGL with the
amino acid sequence shown as SEQ ID NO.1. The beta-glycosidase SS-BGL mutant is obtained by conducting single-site
mutation or double-site mutation on beta-glycosidase SS-BGL with the
amino acid sequence shown as SEQ ID NO.2. Wherein the
single site mutation is that
phenylalanine at the 229 site of SEQ ID NO. 1 is mutated into
proline; the double-site mutation is as follows:
phenylalanine at the 229 site in SEQ ID NO. 1 is mutated into
proline, and
glycine at the 301 site is mutated into
proline; or the
phenylalanine at the 229 site in SEQ ID NO. 1 is mutated into proline, and the
leucine at the 337 site is mutated into
valine; or the phenylalanine at the 229 site in SEQ ID NO. 1 is mutated into the proline, and the
glycine at the 338 site is mutated into the proline. On the basis of natural beta-glycosidase SS-BGL, the molecular structure of the beta-glycosidase SS-BGL is modified through site-
directed mutagenesis, and four beta-glycosidase SS-BGL mutants with the
saponin conversion activity improved are obtained.