β-Galactosidase (lactase) is a glycoside hydrolase. β-Galactosidasecatalyzes catalyzes reactions with β-d-galactopyranosides with an oxygen glycosidic bond.
[1]. Juers DH, et al. LacZ β-galactosidase: structure and function of an enzyme of historical and molecular biological importance. Protein Sci. 2012 Dec;21(12):1792-807.