Enhancing laccase activity using pro-oxidants and pro-degradants

Abstract

A two-component mediator system is disclosed, wherein one component serves as a pro-oxidant and the other component serves as a pro-degradant and booster. When used in combination with a laccase, the two-component mediators enhance the bleaching of pulp. In addition, a composition comprising an oxidative enzyme, a pro-oxidant, and a pro-degradant, and a process for oxidizing a substrate that comprises treating the substrate with an oxidizing enzyme, a pro-oxidant, and a pro-degradant are disclosed. The pro-oxidant can be ascorbic acid, ascorbate, salicylic acid, salicylate, nicotinic acid, nicotinate, a hardwood black liquor, a softwood black liquor, ligno-organosolv, lignin sulfonate, or mixtures thereof. The pro-degradant can be urea, thiourea, sulfamic acid, sulfamide, guanidine, methylsulfonic acid, or mixtures thereof.

What is claimed is:  
     
         1 . A process for bleaching a lignin-containing material, comprising treating the material with an oxidative enzyme, a pro-oxidant, and a pro-degradant.  
     
     
         2 . The process of  claim 1  wherein said oxidative enzyme is a laccase, a catechol oxidase, a monophenol monooxygenase, a bilirubin oxidase, or a mixture thereof.  
     
     
         3 . The process of  claim 1  further comprising adding a hydrolase.  
     
     
         4 . The process of  claim 3  wherein said hydrolase is xylanase.  
     
     
         5 . The process of  claim 1  further comprising adding an oxidizing agent.  
     
     
         6 . The process of  claim 5  where said oxidizing agent is at least one of air, oxygen, and hydrogen peroxide.  
     
     
         7 . The process of  claim 1  wherein said pro-oxidant is ascorbic acid, ascorbate, salicylic acid, salicylate, nicotinic acid, nicotinate, a hardwood black liquor, a softwood black liquor, ligno-organosolv, lignin sulfonate, or a mixture thereof.  
     
     
         8 . The process of  claim 1  where said pro-degradant is urea, thiourea, sulfamic acid, sulfamide, guanidine, methylsulfonic acid, or a mixture thereof.  
     
     
         9 . The process of  claim 1  wherein said material is a wood pulp.  
     
     
         10 . The process of  claim 9  wherein said wood pulp is a raw material used to form a cellulose or a cellulose derivative.  
     
     
         11 . A process for oxidizing a substrate, wherein said process comprises treating the substrate with an oxidizing enzyme, a pro-oxidant, and a pro-degradant.  
     
     
         12 . The process of  claim 11  wherein said oxidizing enzyme is a laccase, a catechol oxidase, a monophenol monooxygenase, a bilirubin oxidase, or a mixture thereof.  
     
     
         13 . The process of  claim 11  that further comprises adding an oxidizing agent.  
     
     
         14 . The process of  claim 13  wherein said oxidizing agent is at least one of air, oxygen, and hydrogen peroxide.  
     
     
         15 . The process of  claim 11  wherein said pro-oxidant is ascorbic, ascorbate, salicylic acid, salicylate, nicotinic acid, nicotinate, a hardwood black liquor, a softwood black liquor, ligno-organosolv, lignin sulfonate, or a mixture thereof.  
     
     
         16 . The process of  claim 11  wherein said pro-degradant is urea, thiourea, sulfamic acid, sulfamide, guanidine, methylsulfonic acid, or a mixture thereof.  
     
     
         17 . The process of  claim 11  that further comprises adding an oxidizing agent.  
     
     
         18 . The process of  claim 17  wherein said oxidizing agent is at least one of air, oxygen, and hydrogen peroxide.  
     
     
         19 . A composition comprising an oxidative enzyme, a pro-oxidant, and a pro-degradant.  
     
     
         20 . The composition of  claim 19 , wherein said oxidative enzyme is a laccase, a catechol oxidase, a monophenol monooxygenase, a bilirubin oxidase, or a mixture thereof.  
     
     
         21 . The composition of  claim 19  that further comprises a hydrolase.  
     
     
         22 . The composition of  claim 21  wherein said hydrolase is xylanase.  
     
     
         23 . The composition of  claim 19  wherein said pro-oxidant is ascorbic acid, ascorbate, salicylic acid, salicylate, nicotinic acid, nicotinate, a hardwood black liquor, a softwood black liquor, ligno-organosolv, lignin sulfonate, or a mixture thereof.  
     
     
         24 . The composition of  claim 19  wherein said pro-degradant is urea, thiourea, sulfamic acid, sulfamide, guanidine, methylsulfonic acid, or a mixture thereof.  
     
     
         25 . A two-component mediator for use in a laccase-mediator system, said two-component mediator comprising (i) a pro-oxidant and (ii) a pro-degradant.  
     
     
         26 . The mediator of  claim 25  wherein: 
 (i) said pro-oxidant is ascorbic acid, ascorbate, salicylic acid, salicylate, nicotinic acid, nicotinate, a hardwood black liquor, a softwood black liquor, ligno-organosolv, lignin sulfonate, or a mixture thereof; and  
 (ii) said pro-degradant is urea, thiourea, sulfamic acid, sulfamide, guanidine, methylsulfonic acid, or a mixture thereof.