Highly active xylose reductase from neurospora crassa

Abstract

A new xylose reductase encoding gene from Neurspora crassa was heterologously expressed in E. coli as a His-tag fusion protein and subsequently purified in high yield. This xylose reductase was shown to have a high turnover rate and catalytic efficiency, high stability at room temperature, broad pH profile, and a preference of NADPH over NADH. This enzyme is utilized in production of xylitol and other sugar alcohols such as sorbitol and also in the metabolic enhancement of organisms used for fermentation of plant biomass into ethanol.

1 - 14 . (canceled) 
     
     
         15 . Use of a purified xylose reductase comprising the amino acid sequence of SEQ ID NO: 2 to produce ethanol. 
     
     
         16 . The use of  claim 15 , wherein the production of ethanol is by fermentation. 
     
     
         17 . Use of a purified xylose reductase comprising the amino acid sequence of SEQ ID NO: 2 to metabolically enhance an organism used for fermentation of a plant biomass to produce ethanol. 
     
     
         18 . A method of producing ethanol, the method comprising:
 (a) obtaining a highly active form of xylose reductase comprising an amino acid sequence of SEQ ID NO: 2 or an amino acid sequence that is 90% similar to the amino acid sequence of  Neurospora crassa  xylose reductase as in SEQ ID NO: 2; and   (b) providing conditions to produce ethanol from a xylose containing medium.   
     
     
         19 . (canceled) 
     
     
         20 . The method of  claim 18 , wherein the xylose reductase is expressed in a heterologous host. 
     
     
         21 - 23 . (canceled) 
     
     
         24 . The method of  claim 18 , wherein the xylose reductase is produced by a fermentation process.