beta (beta)-galactosidase

be·ta (β)-ga·lac·to·sid·ase

(bā'tă-ga-lak-tō'si-dās) An enzyme that hydrolyzes the β-galactoside linkage in lactose-producing glucose and galactose; also hydrolyzes the chromogenic substrate IPTG (isopropylthiogalactoside) and thus is used as an indicator of fused genes and gene expression.