title: Computational simulations of the Trichoderma reesei cellobiohydrolase I acting on microcrystalline cellulose Ibeta: the enzyme-substrate complex.
abstract: Cellobiohydrolases are the dominant components of the commercially relevant Trichoderma reesei cellulase system. Although natural cellulases can totally hydrolyze crystalline cellulose to soluble sugars, the current enzyme loadings and long digestion times required render these enzymes less than cost effective for biomass conversion processes. It is clear that cellobiohydrolases must be improved via protein engineering to reduce processing costs. To better understand cellobiohydrolase function, new simulations have been conducted using charmm of cellobiohydrolase I (CBH I) from T.reesei interacting with a model segment (cellodextrin) of a cellulose microfibril in which one chain from the substrate has been placed into the active site tunnel mimicking the hypothesized configuration prior to final substrate docking (i.e., the +1 and +2 sites are unoccupied), which is also the structure following a catalytic bond scission. No tendency was found for the protein to dissociate from or translate along the substrate surface during this initial simulation, nor to align with the direction of the cellulose chains. However, a tendency for the decrystallized cellodextrin to partially re-anneal into the cellulose surface hints that the arbitrary starting configuration selected was not ideal.
authors.affiliation: Department of Food Science, Cornell University, Ithaca, NY 14853, United States.
authors.forename: Linghao
authors.initials: L
authors.lastname: Zhong
authors.forename: James F
authors.initials: JF
authors.lastname: Matthews
authors.forename: Peter I
authors.initials: PI
authors.lastname: Hansen
authors.forename: Michael F
authors.initials: MF
authors.lastname: Crowley
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Cleary
authors.forename: Ross C
authors.initials: RC
authors.lastname: Walker
authors.forename: Mark R
authors.initials: MR
authors.lastname: Nimlos
authors.forename: Charles L
authors.initials: CL
authors.lastname: Brooks
authors.forename: William S
authors.initials: WS
authors.lastname: Adney
authors.forename: Michael E
authors.initials: ME
authors.lastname: Himmel
authors.forename: John W
authors.initials: JW
authors.lastname: Brady
mesh_terms: D001665:Binding Sites; D002482:Cellulose / Q000737:chemistry* / Q000378:metabolism*; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000737:chemistry* / Q000378:metabolism*; D003198:Computer Simulation; D007700:Kinetics; D008956:Models, Chemical; D015394:Molecular Structure; D017433:Protein Structure, Secondary; D013816:Thermodynamics; D014242:Trichoderma / Q000201:enzymology*
chemical_list: D002482:Cellulose; D043366:Cellulose 1,4-beta-Cellobiosidase