Product inhibition of five Hypocrea jecorina cellulases

► A calorimetric approach to cellulase product inhibition has been developed. ► The assay uses unmodified, insoluble cellulose as substrate. ► Glucose- and cellobiose inhibition was quantified for five H. jecorina cellulases. ► The strongest inhibition was found for Cel7A/cellobiose and Cel6A/glucose. ► The activity of Cel5A was only weakly affected by the two investigated products.