Reducing content of hexenuronic acids in cellulosic pulp
The present invention provides an enzymatic method for reducing the content of hexenuronic acids in a chemical cellulosic pulp and/or improvement of the brightness of cellulosic pulp using haloperoxidase.
1. A method for reducing the content of hexenuronic acids in and/or improving the brightness of a cellulosic pulp, said method comprising:
contacting said pulp with a haloperoxidase comprising an amino acid sequence that is at least 95% identical to SEQ ID NO: 1, hydrogen peroxide, and chloride, bromide, iodide, and/or thiocyanate ions.
2. The method of claim 1 , wherein said haloperoxidase comprises an amino acid sequence that is at least 97% identical to SEQ ID NO: 1.
3. The method of claim 1 , wherein said haloperoxidase comprises an amino acid sequence that is 100% identical to SEQ ID NO: 1.
4. The method of claim 1 , further comprising contacting said pulp with a xylanase.
5. The method of claim 1 , further comprising contacting said pulp with an endo-1,4-beta-xylanase from enzyme class EC 3.2.1.8.
6. The method of claim 1 , further comprising contacting said pulp with a xylanase comprising an amino acid sequence that is at least 95% identical to SEQ ID NO: 3.
7. The method of claim 1 , further comprising contacting said pulp with a xylanase comprising an amino acid sequence that is at least 97% identical to SEQ ID NO: 3.
8. The method of claim 1 , wherein said pulp is a pulp made by alkaline cooking.
9. An aqueous composition, comprising:
a cellulosic pulp comprising one or more hexenuronic acids;
a haloperoxidase comprising an amino acid sequence that is at least 95% identical to SEQ ID NO: 1;
hydrogen peroxide; and
chloride, bromide, iodide, or thiocyanate ions.
10. The composition of claim 9 , wherein said pulp is a pulp made by alkaline cooking.
11. The composition of claim 9 , further comprising a xylanase.
12. The method of claim 1 , further comprising contacting said pulp with a xylanase comprising an amino acid sequence is 100% identical to SEQ ID NO: 3.
13. The method of claim 1 , further comprising contacting said pulp with one or more tertiary amines.
14. A method for reducing the content of hexenuronic acids in and/or improving the brightness of a cellulosic pulp, said method comprising:
contacting said pulp with a haloperoxidase comprising an amino acid sequence that is 100% identical to SEQ ID NO:1; a xylanase comprising an amino acid sequence that is 100% identical to SEQ ID NO: 3; hydrogen peroxide; and chloride, bromide, iodide, and/or thiocyanate ions.
15. The method of claim 14 , further comprising contacting said pulp with one or more tertiary amines.
16. The composition of claim 9 , wherein said haloperoxidase comprises an amino acid sequence that is at least 97% identical to SEQ ID NO: 1.
17. The composition of claim 9 , wherein said haloperoxidase comprises an amino acid sequence that is 100% identical to SEQ ID NO: 1.
18. The composition of claim 11 , wherein said xylanase comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 3.
19. The composition of claim 11 , wherein said xylanase comprises an amino acid sequence that is at least 97% identical to SEQ ID NO: 3.
20. The composition of claim 11 , wherein said xylanase comprises an amino acid sequence that is 100% identical to SEQ ID NO: 3.