Enzyme Optimization Group
There has been significant progress over several decades in producing cost-effective enzymes for enhanced hydrolysis of biomass into fermentable monomeric sugars. However, several obstacles remain before these enzymes are able to provide optimal sugar yields at cost-effective levels. Foremost, a fundamental and applied understanding of the three major classes of biomass degrading enzymes (cellulases, hemicellulases and lignases) is needed to effectively maximize liberation of monomeric sugars from pretreated biomass. To date, only a few cellulase systems have been well characterized or optimized, and there is significantly less known about hemicellulases and lignases. Moreover, little is currently known about enzyme activity as a function of the type of pretreatment, type of biomass, or targeted biorefinery operating conditions. Understanding the mode of action of both free enzymes and enzyme complexes is an important first step in developing enzymes with greater hydrolytic efficiency and stability. To develop enzyme cocktails that are optimized for both substrates of interest and industrially relevant conditions, we are characterizing and engineering targeted sets of lingocellulolytic enzymes that can tolerate industrial processing conditions such as extremes of temperature and pH, as well as the presence of ionic liquids. In addition, we are integrating new enzymes identified by the Deconstruction Division's Microbial Communities team. These efforts rely on structure- and sequence-based approaches to enzyme engineering and new high-throughput screening techniques developed by the Technologies Division.
Figure 1. Crystal structure of an endocellulase isolated from Alicyclobacillus acidocaldarius. (From JBEI paper: Pereira J.H., Sapra R., Volponi J.V., Kozina C.L., Simmons B.A., and Adams P.D. Structure of endoglucanase Cel9A from the thermoacidophilic Alicyclobacillus acidocaldarius. Acta Crystallographica, Section D: Biological Crystallography, D65(8), 744-750, 2009)
Objectives
- Develop optimized enzyme cocktails tailored for specific chemical environments that efficiently liberate monomeric sugars from pretreated biomass.
- Develop engineered enzymes that are optimized for activity in targeted cocktails.
- Develop a fundamental understanding of how enzymes interact with substrates.
- Generate new insights into the sequence- and structure-based properties of enzymes that impart thermostability, pH tolerance, ionic liquid tolerance, high specific activity and specificity.
