7-51: Rational design of CBH IIs and BGs for improved activity and thermostability

Efficient hydrolysis of biomass requires multiple enzyme activities. These enzymes must be able to hydrolyze a range of biomass feedstocks. At Novozymes we have developed a robust, versatile enzyme cocktail with increased catalytic activity and thermostability, and improved tolerance to inhibition. Our recent and continued success results from continued searching in natural diversity, engineering improved specific activity and thermostability of the enzymes present in our existing cellulase products, addition of accessory proteins that improve performance on some substrates, and introduction of superior proteins into a Trichoderma reesei cellulase mixture. Two major components of this enzyme cocktail are the cellobiohydrolase II (CBH II) and the beta-glucosidase (BG).  The CBHII hydrolyzes cellulose oligomers into cellobiose while the BG hydrolyzes cellobiose to glucose.  Using consensus sequence analysis and structural modeling we have identified several variants of CBH IIs and variants of BGs that either increased their thermostability or significantly improved the enzyme’s specific activity and in one case, an improvement to both.