S. Karita et al., CELLULOSE-BINDING DOMAINS CONFER AN ENHANCED ACTIVITY AGAINST INSOLUBLE CELLULOSE TO RUMINOCOCCUS-ALBUS ENDOGLUCANASE-IV, Journal of fermentation and bioengineering, 81(6), 1996, pp. 553-556
The gene encoding cellulose-binding domains (CBDs) from Clostridium st
ercorarium xylanase A was joined to the egIV gene encoding endoglucana
se IV (EGIV) from Ruminococcus albus. The hybrid protein (EGIV + CBD)
expressed from this fusion gene in Escherichia coli acquired the abili
ty to adsorb onto insoluble celluloses such as ball-milled cellulose (
BMC). EGIV + CBD was more active toward BMC at low concentrations than
the parental enzyme, EGIV, although there was no difference in the ca
talytic properties between them toward carboxymethyl cellulose. This r
esult indicates that the addition of the CBDs to EGIV enhances enzyme
activity on the insoluble cellulose by concentrating the catalytic dom
ain on the substrate surface.