## 2 Mechanism of Action
### Impact of Amphiphiles on Enzyme Desorption  
According to a proposed model (Figure 2), if polymers of PEG are used at certain concentration on the adsorbed surface, then at the time of the contact of protein of interest (e.g., enzyme) with polymer (e.g., formed mushroom regime), one of the strands of polymer would be squeezed out from the beneath the enzyme pushing the protein into solution due to increased entropy. As enzyme activity and enzyme concentration should have a direct correlation at an optimum condition of pH, temperature and shear rate [61], an evaluation of product concentration that is also correlated with enzyme concentration can be used to evaluate enzyme activity. To be able to assess the enzyme concentration at a specific time point, it is helpful to first study the adsorption equilibrium of the enzyme. [PERSON] _et al._[12] showed that the equilibrium time for adsorption of dialyzed commercial enzyme (Accelerase(tm)1000) to cellulosic substrate was reported to be 45 min for cellulosic biomass (with 4.2% lignin) and 60 min for isolated lignin. However, according to [PERSON] _et al._[64] the adsorption of Cel7A (CBH I) to substrate increased constantly from 30 min up to 300 min. This author also reported that the adsorption of Cel7A to SPS was reversible after 24 h. In addition, when adsorption of \(\beta\)-glucosidase was studied during the hydrolysis of PNPG, 60% of the initial enzyme activity was found on liquid phase and 40% in solid phase. The result of analysis conducted with SDS-PAGE and sugar yield showed a rapid initial adsorption of this enzyme to substrate followed by immediate desorption in the solution [64]. Figure 2: The escape transition following protein compression of a PEG polymer that has been adsorbed to the surface in mushroom regime. (Adopted from [PERSON] _et al._[62], based on [PERSON] _et al._[63]). Uncompress (**I**), Compressed (**II**), Chain escape (**III**). However other authors such as [PERSON] _et al._[65] and [PERSON] _et al._[66] have found that for Kraft wood and soft wood, the majority of CBHs (cellubiohydrolase) and EGs (endoglucanase) were adsorbed to lignin and were not re-solubilized in solution after the completion of cellulose hydrolysis. Typically, at the first step of the hydrolysis, cellulase adsorbs to both active and non-active sites of the biomass, and as the reaction progresses, the enzymes that were adsorbed to the active sites start being released into the solution when cellulosic carbohydrate digestion evolves [34, 67]. [PERSON] _et al._[68] tested the impact of Tween 20 on adsorption of endoglucanase I (_Endo_I) and exoglucanase II (_Exo_II) using microcrystalline cellulose as the substrate. As a result it was found that in the presence of Tween 20 the adsorption of _Exo_I to cellulose was enhanced, while the desorption of _Exo_II from insoluble substrate was enhanced. According to [PERSON] _et al._[68], the increase in hydrolytic performance of cellulase by Tween 20 was attributed to both activation of _Exo_II and partial defibrillation of cellulose. The analysis for the protein content of the supernatant of native CBH1 and core CBH1 of a solution containing Tween 80-treated ball milled cellulose (BMC) demonstrated reduced adsorption of both native CBH1 and core CBH1 onto BMC [19]. Furthermore, [PERSON] _et al._[53] reported that Tween 20 lowered the non-biospecific adsorption of \(\beta\)-glucosidase and increased the bio-specific adsorption of cellulase onto cellulose at reduced or non-hydrolytic temperature. The result of another study showed that, commercial enzyme (Ctec\({}_{2}\)) was adsorbed on both pure cellulose and biomass, and after 24 h hydrolysis, 20.6% (1.71% out of 8.29% _w/w_) and 9.5% (0.79% out of 8.29% _w/w_) of enzymes were adsorbed to the Avicel and extruded corn stover (CS), respectively. After the addition of PEG the adsorption of enzyme was decreased by 14.0% for Avicel and by 20.2% for CS [36].