Table 1 Functional and structural properties of cellulases

Endoglucanases

EC 3.2.1.4

Breaks internal linkages of cellulose molecules, producing cellobiose and possesses rapid dissociation capacity

They possess short loops that stick along cellulose chains to yield long-chain oligomers

[27, 39]

Exoglucanases or Cellobiohydrolases,

EC 3.2.1.74

Cleave the same glycosidic bond from terminal ends of cellulose molecules, producing cellobiose

They possess long loops and attracted to crystalline sites along cellulose microfibril chains and produce mainly Cellodextrin

It exists in two forms based on the part of the oligosaccharide chain that is attacked. The reducing end and non-reducing end of cellobiohydrolase

[27, 39, 40]

β-glucosidases or cellobiases

EC 3.2.1.21

Cleaves cellobiose into two glucose molecules

It has a solid structure with the functioning site within a pocket which permits the entry of disaccharides. It has 2 forms which catalyze hydrolysis either from the reducing chain ends or the non-reducing chain ends

[22, 27, 41]