Alpha-amylase mutants

Abstract

The invention relates to a variant of a parent Termamyl-like α-amylase, which exhibits an alteration in at least one of the following properties relative to said parent α-amylase: i) improved pH stability at a pH from 8 to 10.5; and/or ii) improved Ca 2+ stability at pH 8 to 10.5, and/or iii) increased specific activity at temperatures from 10 to 60° C.

1 . A variant alpha-amylase of a parent alpha-amylase, wherein the variant has alpha-amylase activity, and at least 95% homology with the amino acid sequence shown in SEQ ID. NO. 3 comprising one or more of the following substitutions (using SEQ ID NO: 3 for numbering):
 I181A,R,N,C,E,Q,G,H,L,K,M,F,P,S,T,W,Y, or V, wherein the variant has increased specific activity relative to the parent alpha-amylase, wherein specific activity is determined at a temperature of 10° C. to 60° C.   
     
     
         2 . The variant of  claim 1 , wherein the variant comprises a substitution of I181A. 
     
     
         3 . The variant of  claim 1 , wherein the variant comprises a substitution of I181R. 
     
     
         4 . The variant of  claim 1 , wherein the variant comprises a substitution of I181N. 
     
     
         5 . The variant of  claim 1 , wherein the variant comprises a substitution of I181C. 
     
     
         6 . The variant of  claim 1 , wherein the variant comprises a substitution of I181E. 
     
     
         7 . The variant of  claim 1 , wherein the variant comprises a substitution of I181Q. 
     
     
         8 . The variant of  claim 1 , wherein the variant comprises a substitution of I181G. 
     
     
         9 . The variant of  claim 1 , wherein the variant comprises a substitution of I181H. 
     
     
         10 . The variant of  claim 1 , wherein the variant comprises a substitution of I181L. 
     
     
         11 . The variant of  claim 1 , wherein the variant comprises a substitution of I181K. 
     
     
         12 . The variant of  claim 1 , wherein the variant comprises a substitution of I181M. 
     
     
         13 . The variant of  claim 1 , wherein the variant comprises a substitution of I181F. 
     
     
         14 . The variant of  claim 1 , wherein the variant comprises a substitution of I181P. 
     
     
         15 . The variant of  claim 1 , wherein the variant comprises a substitution of I181S. 
     
     
         16 . The variant of  claim 1 , wherein the variant comprises a substitution of I181T. 
     
     
         17 . The variant of  claim 1 , wherein the variant comprises a substitution of I181W. 
     
     
         18 . The variant of  claim 1 , wherein the variant comprises a substitution of I181Y. 
     
     
         19 . The variant of  claim 1 , wherein the variant comprises a substitution of I181V. 
     
     
         20 . A variant alpha-amylase of a parent alpha-amylase, which variant has alpha-amylase activity and at least 95% homology with the amino acid sequence shown in SEQ ID. NO. 3, comprising a substitution (using SEQ ID NO: 3 for numbering):
 at position 181, wherein the variant has increased specific activity relative to the parent alpha-amylase, wherein the specific activity is determined at a temperature of 20° C. to 50° C.