Fine substrate specificities of four exo-type cellulases produced by Aspergillus niger, Trichoderma reesei, and Irpex lacteus on (1-->3), (1-->4)-beta-D-glucans and xyloglucan.
To investigate the fine substrate specificities of four highly purified exo-type cellulases (Exo-A from Aspergillus niger, CBHI and CBHII from Trichoderma reesei, and Ex-1 from Irpex lacteus), water-soluble substrates such as barley glucan, xyloglucan from tamarind (Tamarindus indica L.), and their oligosaccharides were employed. Four exo-type cellulases immediately hydrolyzed 3-O-beta-D-cellotriosylglucose to produce cellobiose and laminaribiose. In contrast, CBHII showed no hydrolytic activity towards 3(2)-O-beta-D-cello-biosylcellobiose, which was hydrolyzed to cellobiose by the other exo-type cellulases. These cellulases hydrolyzed the internal linkages of barley glucan and lichenan in an endo-type fashion to produce cellobiose and mix-linked oligosaccharides as main products. The DP-lowering activities of the four exo-type cellulases on barley glucan were in the order of Ex-1, CBHII, Exo-A, and CBHI. Based on gel permeation chromatography analysis of the hydrolysates, Ex-1 seemed to attack the internal cellobiosyl unit adjacent to beta-1,3-glucosidic linkages in barley glucan molecule more frequently than did the other cellulases. Xyloglucan was hydrolyzed only by CBHI and CBHII, and produced hepta-, octa-, and nona-saccharides. In addition, a xyloglucan tetradecasaccharide (XG14) was split only to heptasaccharide (XG7) by CBHI and CBHII.
Amano
Y
Y
Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Nagano. yoamano@gipwc.shinshu-u.ac.jp
Shiroishi
M
M
Nisizawa
K
K
Hoshino
E
E
Kanda
T
T
D001234:Aspergillus niger / Q000201:enzymology*; D002480:Cellulase / Q000737:chemistry* / Q000378:metabolism; D043366:Cellulose 1,4-beta-Cellobiosidase; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D005936:Glucans / Q000378:metabolism; D006026:Glycoside Hydrolases; D011134:Polysaccharides / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014242:Trichoderma / Q000201:enzymology*; D014990:Xylans; D001616:beta-Galactosidase / Q000737:chemistry* / Q000378:metabolism
D005656:Fungal Proteins; D005936:Glucans; D011134:Polysaccharides; D014990:Xylans; C029353:xyloglucan; D006026:Glycoside Hydrolases; C063901:exo-beta-(1--3)-D-galactanase; D001616:beta-Galactosidase; D002480:Cellulase; D043366:Cellulose 1,4-beta-Cellobiosidase; C015968:lichenin