Skip to main content

Table 5 Important conditions simulated in the model for enzymatic hydrolysis of cellulose by enzymes from endo, exo and β-glucosidase classes

From: Stochastic molecular model of enzymatic hydrolysis of cellulose for ethanol production

Enzyme class

Conditions/assumptions

Endo-cellulase (EG, Non-processive action pattern by an enzyme that contains a CBM)

• Lower probability of breaking bond in crystalline region compared to those in amorphous regions

 

• Probability of binding to the glucose chain and hydrolysis of bonds located on EF surface but not on MF surface is 25% lower compared to the glucose chains on the both EF and MF surfaces

 

• A minimum number of glucose molecules, depending upon size of enzyme, are required to be unblocked (not blocked by other enzymes) and on the EF surface to enable binding (please see section A3 of Additional file 1)

 

• Enzymes do not act on oligomers of chain length less than five. The enzymes can hydrolyze bonds to produce glucose with a defined 90% probability. Inhibition occurs due to cellobiose and glucose [1, 54]

Exo-cellulase (CBH I, Processive action pattern by an enzyme that may/may not have a CBM.)

• Probability of binding to the glucose chain and hydrolysis of bonds located on EF surface but not on MF surface is 25% lower compared to the glucose chains on the both EF and MF surfaces

 

• These enzymes have higher probability of hydrolysis with shorter glucose chains compared to longer chains [20]. A preferred chain length of 300 glucose molecules was assumed

 

• Enzyme may get desorbed from the glucose chains at any time. Probability of desorption in amorphous region (5.0%) was set higher than that in crystalline region (2.5%)

 

• Enzymes have lower probability of bond hydrolysis in the case of soluble oligomers and do not act on oligomers with DP<5

 

• Inhibition occurs due to cellobiose and glucose, however cellobiose is a stronger inhibitor [1, 19, 50, 54]

β-glucosidase

• Acts only on soluble chains (DP<6)

 

• Probability of action on cellobiose is higher than other soluble oligosaccharides

 

• Inhibited by glucose