Cellobiohydrolase enzymes depolymerise cellulose into its fundamental repeating unit of two glucose molecules (cellobiose). These enzymes are key components of fungal cellulase multienzyme systems; together with randomly-acting endo-1,4-beta-glucanases (which cut internal beta-1,4-glucosidic bonds) they hydrolyse cellulose via a processive mechanism, forming cellobiose as a major product. Cellobiose is then converted by beta-glucosidases to glucose; the latter product may further be fermented to ethanol or other liquid fuels and chemicals.

These enzymes suffer from inhibition by this product, which lingers in the enzymes’ active sites and thus delays their catalytic cycles. Cellobiose accumulates over the course of the reaction unless removed by an enzyme such as beta-glucosidase, which cleaves cellobiose yielding two glucose molecules.

This entry represents the Glycoside hydrolase, family 7 (GH7).