Mutant alpha-amylases

Abstract

The invention relates to a mutant α-amylase obtained by making replacement or deletion of at least one of amino acid residues such as the 167th Gln, 169th Tyr and 178th Ala in the amino acid sequence set forth in SEQ ID NO:1 in an α-amylase having said amino acid sequence, or an α-amylase having a homology of at least 70% to said amino acid sequence, a gene encoding the mutant α-amylase, a vector, transformed cells, a process for producing a mutant α-amylase, comprising culturing the transformed cells, and a detergent composition comprising the mutant α-amylase. The mutant α-amylase of the invention has excellent properties of high resistance to chelating agents, high specific activity in an alkaline region and excellent stability to heat, and is hence useful for detergents for automatic dish washer, laundry detergents and the like.

1 . A gene encoding a mutant α-amylase wherein said mutant α-amylase is obtained by making replacement or deletion of at least one residue of amino acid residues respectively corresponding to the 11th Tyr, 16th Glu, 49th Asn, 84th Glu, 144th Ser, 167th Gln, 169th Tyr, 178th Ala, 188th Glu, 190th Asn, 205th His and 209th Gln in the amino acid sequence set forth in SEQ ID NO: 1 in an α-amylase having said amino acid sequence, or an α-amylase having a homology of at least 70% to said amino acid sequence. 
     
     
         2 . A vector containing a non-human gene encoding the mutant α-amylase according to  claim 1 . 
     
     
         3 . Cells transformed by the vector according to  claim 2 . 
     
     
         4 . A process for producing a mutant α-amylase, comprising culturing the transformed cells according to  claim 3 .