Beta-glucosidase (EC184.108.40.206, gentiobiase, cellobiase, emulsin, elaterase, aryl-beta-glucosidase, beta-D-glucosidase, beta-glucoside glucohydrolase, arbutinase, amygdalinase, p-nitrophenyl beta-glucosidase, primeverosidase, amygdalase, linamarase, salicilinase, beta-1,6-glucosidase) is a glucosidase enzyme that acts upon β1->4 bonds linking two glucose or glucose-substituted molecules (i.e., the disaccharidecellobiose). It is an exocellulase with specificity for a variety of beta-D-glycoside substrates. It catalyzes the hydrolysis of terminal non-reducing residues in beta-D-glucosides with release of glucose.
Cellulose is largely composed of polymers of beta-bond linked glucose molecules, and beta-glucosidases are required by organisms (some fungi, bacteria, termites) that can consume it. These enzymes are a powerful tool for degradation of plant cell walls for pathogens.
Lysozyme, an enzyme secreted in tears to prevent bacterial infection of the eye, is also a beta-glucosidase that cleaves β1→4 bonds between N-acetylglucosamine and N-acetylmuramic acid sugars within the peptidoglycan cell walls of gram-negative bacteria.