Project description:The crystal structure of a secreted chymotrypsin from the alkaliphile Cellulomonas bogoriensis has been determined using data to 1.78 A resolution and refined to a crystallographic R factor of 0.167. The crystal structure reveals a large P1 substrate-specificity pocket, as expected for chymotrypsins. The structure is compared with close structural homologues. This comparison does not reveal clear reasons for the alkali tolerance of the enzyme, but the greater compactness of the structure and lowered hydrogen bonding may play a role.
Project description:DyP-type peroxidases are heme-containing enzymes that have received increasing attention over recent years with regards to their potential as biocatalysts. A novel DyP-type peroxidase (CboDyP) was discovered from the alkaliphilic cellulomonad, Cellulomonas bogoriensis, which could be overexpressed in Escherichia coli. The biochemical characterization of the recombinant enzyme showed that it is a heme-containing enzyme capable to act as a peroxidase on several dyes. With the tested substrates, the enzyme is most active at acidic pH values and is quite tolerant towards solvents. The crystal structure of CboDyP was solved which revealed atomic details of the dimeric heme-containing enzyme. A peculiar feature of CboDyP is the presence of a glutamate in the active site which in most other DyPs is an aspartate, being part of the DyP-typifying sequence motif GXXDG. The E201D CboDyP mutant was prepared and analyzed which revealed that the mutant enzyme shows a significantly higher activity on several dyes when compared with the wild-type enzyme.