Structure determination and analysis of a bacterial chymotrypsin from Cellulomonas bogoriensis

The crystal structure of a secreted chymotrypsin from the alkaliphile Cellulomonas bogoriensis has been determined using data to 1.78 Å 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.