title: Characterization of the catalytic domains of Trichoderma reesei endoglucanase I, II, and III, expressed in Escherichia coli.
abstract: The genes encoding the catalytic domains (CD) of the three endoglucanases (EG I; Cel7B, EG II; Cel5A, and EG III; Cel12A) from Trichoderma reesei QM9414 were expressed in Escherichia coli strains Rosetta-gami B (DE3) pLacI or Origami B (DE3) pLacI and were found to produce functional intracellular proteins. Protein production by the three endoglucanase transformants was evaluated as a function of growth temperature. Maximal productivity of EG I-CD at 15 degrees C, EG II-CD at 20 degrees C and EG III at 37 degrees C resulted in yields of 6.9, 72, and 50 mg/l, respectively. The endoglucanases were purified using a simple purification method based on removing E. coli proteins by isoelectric point precipitation. Specific activity toward carboxymethyl cellulose was found to be 65, 49, and 15 U/mg for EG I-CD, EG II-CD, and EG III, respectively. EG II-CD was able to cleave 1,3-1,4-beta-D-glucan and soluble cellulose derivatives. EG III was found to be active against cellulose, 1,3-1,4-beta-D-glucan and xyloglucan, while EG I-CD was active against cellulose, 1,3-1,4-beta-D-glucan, xyloglucan, xylan, and mannan.
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, 940-21, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Nakazawa
authors.forename: Katsunori
authors.initials: K
authors.lastname: Okada
authors.forename: Ryota
authors.initials: R
authors.lastname: Kobayashi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kubota
authors.forename: Tomoko
authors.initials: T
authors.lastname: Onodera
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Ochiai
authors.forename: Naoki
authors.initials: N
authors.lastname: Omata
authors.forename: Wataru
authors.initials: W
authors.lastname: Ogasawara
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Okada
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Morikawa