Modes of action on cotton and bacterial cellulose of a homologous endoglucanase-exoglucanase pair from Trichoderma reesei.
The endoglucanase I (EGI) and the cellobiohydrolase I (CBHI) of the filamentous fungus Trichoderma reesei form a homologous pair of cellulolytic enzymes which nevertheless have different modes of action. We show here that the action of CBHI on bacterial microcrystalline cellulose results in efficient solubilisation but only a slow decrease in its degree of polymerisation. In contrast, the action of EGI results in a rapid decrease of the degree of polymerisation but less efficient overall solubilisation of the substrate. CBHI alone was practically inactive toward cotton which has a high initial degree of polymerisation and a complex morphology. EGI rapidly reduced the degree of polymerisation of cotton, and slowly solubilised part of it. Working synergistically, EGI and CBHI solubilised cotton more rapidly and to a greater extent than EGI alone. Our data are consistent with the exoglucanase nature of CBHI and also provide some evidence supporting its processive mode of action.
Srisodsuk
M
M
VTT Biotechnology and Food Research, Finland.
Kleman-Leyer
K
K
Keränen
S
S
Kirk
T K
TK
Teeri
T T
TT
D001419:Bacteria; D001665:Binding Sites; D002480:Cellulase / Q000302:isolation & purification / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism*; D043366:Cellulose 1,4-beta-Cellobiosidase; D002852:Chromatography, Ion Exchange; D003460:Crystallization; D003368:Gossypium; D013379:Substrate Specificity; D014242:Trichoderma / Q000201:enzymology*
D002482:Cellulose; D002480:Cellulase; D043366:Cellulose 1,4-beta-Cellobiosidase