Mutant .alpha.-amylase

• US 5,958,739 A
• Filed: 02/20/1997
• Issued: 09/28/1999
• Est. Priority Date: 06/06/1996
• Status: Expired due to Term

• Current Assignee: Genencor International Incorporated (International Flavors & Fragrances Incorporated)
• Original Assignee: Genencor International Incorporated (International Flavors & Fragrances Incorporated)
• Inventors: Mitchinson, Colin, Solheim, Leif P., Day, Anthony, Ropp, Traci, Ringer, Christopher, Requadt, Carol
• Primary Examiner(s): Wax, Robert A.
• Assistant Examiner(s): Stole, Einar
• Application Number:
  US08/704,706
• Time in Patent Office: 950 Days
• Field of Search: 435/204, 435/320.1, 435/252.3, 435/99, 435/201, 435/202, 435/203, 435/252.31, 435/254.11, 435/325, 435/410, 510/226, 510/300, 510/305, 510/320, 510/37 A, 510/392, 536/23.2
• US Class Current: 435/99
• CPC Class Codes: C12N 9/2417 from microbiological source
• CPC Class Codes: C12Y 302/01001 Alpha-amylase (3.2.1.1)

Abstract

Novel α-amylase enzymes are disclosed in which one or more asparagine residues are substituted with a different amino acid or deleted. The disclosed α-amylase enzymes show altered or improved low pH starch hydrolysis performance, stability and activity profiles.

Claims

1. An α

-amylase that is the expression product of a mutated DNA sequence encoding an α

-amylase, the mutated DNA sequence being derived from a precursor α

-amylase by substitution corresponding to N188T.

2. The α

-amylase according to claim 1, wherein said substitution or substitution further comprises the deletion or substitution of a methionine or tryptophan residue.

3. The α

-amylase according to claim 2, wherein said substitution or substitution of said methionine or tryptophan residue comprises a substitution or deletion corresponding to M15, W138 or M197 in Bacillus licheniformis.

4. The α

-amylase according to claim 1 wherein said substitution or substitution further comprises the deletion or substitution of a residue corresponding to V129, H133, S187 or A209 in Bacillus licheniformis.

6. The α

-amylase according to claim 3, wherein said substitution of said methionine residues comprises a substitution corresponding to M15T, W138Y or M197T in Bacillus licheniformis.

7. The α

-amylase according to claim 1, wherein said precursor α

-amylase is derived from Bacillus.

8. The α

-amylase according to claim 7, wherein said precursor α

-amylase is derived from Bacillus licheniformis.

9. A DNA encoding the α

-amylase according to claim 1.

10. A DNA encoding the α

-amylase according to claim 3.

11. A DNA encoding the α

-amylase according to claim 4.

13. An expression vector comprising the DNA of claim 9.

14. An expression vector comprising the DNA of claim 10.

15. An expression vector comprising the DNA of claim 11.

17. A host cell transformed with the expression vector of claim 13.

18. A host cell transformed with the expression vector of claim 14.

19. A host cell transformed with the expression vector of claim 15.

21. An α

-amylase according to claims 1, 4 or 5 having enhanced low pH performance.

22. A detergent composition comprising the α

-amylase according to claims 1, 4 or 5.

23. The detergent composition according to claim 22, wherein said detergent is useful in laundering soiled fabric.

24. The detergent composition according to claim 22, wherein said detergent is useful in washing soiled dishes.

25. A method of liquefying starch comprising the steps of:

(a) preparing a solution comprising starch polymer;

(b) combining with said solution of starch polymer the α

-amylase according to claim 1 under conditions and for a time suitable to liquefy said starch polymer.

26. The method of claim 25, wherein said α

-amylase comprises the α

-amylase according to claim 2.

27. The method of claim 25, wherein said α

-amylase comprises the α

-amylase according to claim 3.

28. The method of claim 25, wherein said α

-amylase comprises the α

-amylase according to claim 4.

29. The method of claim 25, wherein said α

-amylase comprises the α

-amylase according to claim 5.

30. The method of claim 25, wherein said α

-amylase comprises the α

-amylase according to claim 6.

31. The method of claim 25, wherein said α

-amylase comprises the α

-amylase according to claim 7.

32. The method of claim 25, wherein said α

-amylase comprises the α

-amylase according to claim 8.

5. An α

-amylase that is the expression product of a mutated DNA sequence encoding an α

-amylase, the mutated DNA sequence being derived from a precursor α

-amylase by a substitution corresponding to M15T/N188S, M15L/N188S, M15T/H133Y/N188S, M15T/H133Y/N188S/A209V, M15T/N188S/A209V, M15T/V128E/H133Y/N188S, M15T/S187D/N188S, M15T/N188T, M15L/N188T, M15T/H133Y/N188T, M15T/H133Y/N188T/A209V, M15T/N188T/A209V. M15T/V128E/H133Y/N188T, M15T/S187D/N188T in Bacillus licheniformis.

12. A DNA encoding the α

-amylase according to claim 5.

16. An expression vector comprising the DNA of claim 12.

20. A host cell transformed with the expression vector of claim 16.