| 摘要 |
PROBLEM TO BE SOLVED: To obtain a new mutant pullulanase, having excellent resistance to an oxidizing agent by deleting one or more methionine residues in amino acid residues constituting the pullulanase or substituting the one or more methionine residues with an optional amino acid residue other than Cys and Met. SOLUTION: This new mutant pullulanase is obtained by deleting at least one methionine residue in amino acid residues constituting the pullulanase or substituting the methionine residue with an optional amino acid residue other than Cys and Met, has excellent resistance to an oxidizing agent and is varied in the optimal pH and useful for wide applications such as formulation in a detergent composition containing a bleaching agent formulated therein, a composition, etc., for saccharifying starch. As a result of various investitations of a base sequence of a pullulanase gene derived from a Bacillus sp. KSM-1378 strain on a change in properties due to a site-specific variation, it is found that the methionine residue contributes to the inactivation with the oxidizing agent. The mutant pullulanase is obtained by providing a structure in which the methionine residue is deleted or substituted with the other amino acids residue and expressing the gene. |
