Modification of the properties of a Ruminococcus albus endo-1,4-beta-glucanase by gene truncation

An endo-1,4-beta-glucanase (EgI) gene isolated from Ruminococcus albus was deleted at the 5'-flanking region by gene truncation or at the 3'-flanking region by insertion of an omega (omega) fragment with a universal stop codon at the EcoRI or BamHI site. These modified genes were integrated into pUC vectors to construct chimera plasmids for Escherichia coli. The truncated EgIs were produced from transformants (E. coli) harboring the chimera plasmids. An EgI with a 15-amino-acid N-terminal deletion exibited higher activity at lower pH and temperature compared with the activity of the original EgI. The EgIs with 59- and 75-amino-acid deletions from the N and C terminals, respectively, had no activity, indicating that both terminal moieties are essential for enzyme activity.