Open AccessSynergism among three purified cellulolytic components of Clostridium thermocellum
Author(s) -
Singh Ravindra N.,
Akimenko Vasily K.
Publication year - 1994
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1994.tb07177.x
Subject(s) - clostridium thermocellum , cellulase , hydrolysis , cellulose , chemistry , substrate (aquarium) , dithiothreitol , biochemistry , cellulosome , active site , escherichia coli , enzyme , chromatography , biology , ecology , gene
Three clostridial cellulases viz. a hydrophilic cellobiohydrolase (CBH3), a hydrophobic endoglucanase (EG1), and an aggregate‐forming hydrophilic endoglucanase (EG5), all purified from recombinant strains of Escherichia coli , were used in different combinations to reconstitute the synergistic effect during cellulose hydrolysis. EG1 and EG5 were weakly active on crystalline cellulose, if added separately or together in the reaction mixture. However, when CBH3 was added to the reaction mixture, its hydrolytic activity was increased to 1.8‐fold in the presence of EG1 and EG5. A further increase in the activity from 1.8 to 2.2‐fold was observed when calcium and dithiothreitol were added to the reaction mixture containing all three enzymes and filter paper as substrate. The synergistic effect remained unaffected even when EG1 was replaced by its 33‐amino acid C‐terminal deleted variant BL35. BL35 was less active compared to EG1, but was equally hydrophobic as EG1. These results suggest that the hydrophobic interaction between cellulolytic components and/or with the crystalline substrate is important for positive synergistic effect.