The initial kinetics of hydrolysis by cellobiohydrolases I and II is consistent with a cellulose surface-erosion model.
Introduction of a novel method for the quantification of the cellobiose released made it possible to follow the initial stage of hydrolysis of bacterial microcrystalline cellulose (BMCC) by cellobiohydrolases 1,4-beta-D-glucan-cellobiohydrolase I (CBH I) and 1,4-beta-D-glucan-cellobiohydrolase II (CBH II) from Trichoderma reesei. A drastic retardation of the rate of the hydrolysis was observed already at a very low degree of conversion. Earlier-suggested retardation factors, such as product inhibition by cellobiose or enzyme inactivation, could be discounted as primary causes for the pattern. A model including steric hindrance by non-productive binding and erosion of the cellulose surface during the processive action of exoenzymes was proposed to describe the rate retardation observed. Simultaneous action of CBH I and CBH II on cellulose was not a prerequisite for synergy between them.
Väljamäe
P
P
Institute of Molecular and Cell Biology, University of Tartu, Estonia.
Sild
V
V
Pettersson
G
G
Johansson
G
G
D001667:Binding, Competitive; D002480:Cellulase / Q000096:biosynthesis / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry; D043366:Cellulose 1,4-beta-Cellobiosidase; D003198:Computer Simulation; D004794:Enzyme Repression; D005656:Fungal Proteins / Q000096:biosynthesis / Q000737:chemistry*; D006868:Hydrolysis; D007700:Kinetics; D014242:Trichoderma / Q000201:enzymology*
D005656:Fungal Proteins; D002482:Cellulose; D002480:Cellulase; D043366:Cellulose 1,4-beta-Cellobiosidase