Enzymology
Kinetic and molecular dynamics study of inhibition and transglycosylation in Hypocrea jecorina family 3 β-glucosidases
β-Glucosidases enhance enzymatic biomass conversion by relieving cellobiose inhibition of endoglucanases and cellobiohydrolases. However, the susceptibility of these enzymes to inhibition and transglycosylation at high glucose or cellobiose concentrations severely limits their activity and, consequently, the overall efficiency of enzyme mixtures. We determined the impact of these two processes on the hydrolytic activity of the industrially relevant family 3 β-glucosidases from Hypocrea jecorina, HjCel3A and HjCel3B, and investigated the underlying molecular mechanisms through kinetic studies, binding free energy calculations, and molecular dynamics (MD) simulations.Improving the thermal stability of cellobiohydrolase Cel7A from Hypocrea jecorina by directed evolution
Secreted mixtures of Hypocrea jecorina cellulases are able to efficiently degrade cellulosic biomass to fermentable sugars at large, commercially relevant scales. H. jecorina Cel7A, cellobiohydrolase I, from glycoside hydrolase family 7, is the workhorse enzyme of the process. However, the thermal stability of Cel7A limits its use to processes where temperatures are no higher than 50 °C. Enhanced thermal stability is desirable to enable the use of higher processing temperatures and to improve the economic feasibility of industrial biomass conversion.
