Abstract: The invention involves the development of a substrate and assay procedure for the scientific measurement of cellulase in admixture with other enzymes active on cellulose or 1,4-?-D-cello-oligosaccharides, or in various levels of purity of the cellulase. This substrate being characterised by the fact that it contains at least 2 glucose units linked ?-1,4-, with the reducing end glucose unit linked ?- or ?- to a compound which exhibits an optically measurable change on cleavage of the bond between it and the adjacent D-glucosyl residue and the non-reducing terminal D-glucosyl unit is covalently linked to a blocking substituent which inhibits cleavage by exo-acting enzymes of the bond between the terminal and non-reducing end, penultimate D-glucose unit.

Abstract: The invention involves the development of a substrate and assay procedure for the scientific measurement of cellulase in admixture with other enzymes active on cellulose or 1,4-?-D-gluco-oligosaccharides, or in various levels of purity of the cellulase. This substrate being characterised by the fact that it contains at least 2 glucose units linked ?-1,4-, with the reducing end glucose unit linked ?- or ?- to a compound which exhibits an optically measurable change on cleavage of the bond between it and the adjacent D-glucosyl residue and the non-reducing terminal D-glucosyl unit is covalently linked to a blocking substituent which inhibits cleavage by exo-acting enzymes of the bond between the terminal and non-reducing end, penultimate D-glucose unit.