β-galactosidase is a hydrolase enzyme that catalyzes the hydrolysis
of β-galactosides into monosaccharides. Substrates of different
β-galactosidases include ganglioside GM1, lactosylceramides,
lactose, and various glycoproteins.
It is commonly used in molecular biology as a reporter marker to
monitor gene expression. It also exhibits a phenomenon called
α-complementation which forms the basis for the blue/white
screening of recombinant clones. This enzyme can be split in two
peptides, LacZα and LacZΩ, neither of which is active by itself but
when both are present together, spontaneously reassemble into a
functional enzyme.
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