Kinetic and molecular dynamics study of inhibition and transglycosylation in 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 , Cel3A and Cel3B, and investigated the underlying molecular mechanisms through kinetic studies, binding free energy calculations, and molecular dynamics (MD) simulations.

Purification and characterization of a low molecular weight of beta-mannanase from Penicillium occitanis Pol6.

The highest beta-mannanase activity was produced by Penicillium occitanis Pol6 on flour of carob seed, whereas starch-containing medium gave lower enzymes titles. The low molecular weight enzyme was purified to homogeneity by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography procedures. The purified beta-mannanase (ManIII) has been identified as a glycoprotein (carbohydrate content 5%) with an apparent molecular mass of 18 kDa.

Hydrolysis of Nothogenia erinacea xylan by xylanases from families 10 and 11.

The structures of several enzymatic hydrolysis products of Nothogenia erinacea seaweed xylan, a linear homopolymer with mixed beta-(1-->3)/beta-(1-->4) linkages, were analysed by physicochemical and biochemical techniques. With the glycoside hydrolase family 10 beta-(1-->4)-xylanase from Cryptococcus adeliae, hydrolysis proceeds to a final mixture of products containing a mixed linkage-type triose as a major compound, whereas with the family 11 xylanase from Thermomyces lanuginosus this is a mixed linkage tetraose. The Cryptococcus xylanase is shown to be capable of also catalysing the hydrolysis of beta-(1-->3) linkages, that is this of a mixed type tetraose intermediary formed, in accordance with the broader substrate specificity of family 10 enzymes.