β-Galactosidase

β-Galactosidase, a typical glycosidase catalyzing the hydrolysis of glycosidic bonds, is a vital biomarker for cell senescence and cancer occurrence^[1]. Using lactose as a substrate, β-Galactosidase catalyzes sequential galactosyl transfer from lactose to lactose itself or to hydrolysate, galactose or glucose, forming a galacto-oligosaccharides (GOS) mixture containing linear and branched oligosaccharides with polymerization degree of 2-8^[2]. β-Galactosidase has a wide range of substrate specificity, enabling the synthesis of various oligosaccharides or glycosides beyond GOS from different substrates, and facilitates the synthesis of glycoconjugate building blocks, such as ABO blood group determinants, cancer-related carbohydrate antigens and the like^[3]. Main applications of β-Galactosidase for lactose hydrolysis are the production of low-lactose and lactose-free milk and dairy products, and lactase tablets as well as whey syrups^[4].

Definition of activity: One unit causes the formation of one micromole of ONP per minute at pH 7.3 at 37℃.

Properties (the following information is for reference only): White or pale yellow powder, extracted from Escherichia coli. Odorless, slightly sweet. In water, β-Galactosidase is a turbid liquid (mostly dissolved), insoluble in ethanol and acetone. pH range 5.5-9.5 (25℃, 20 hours), optimum pH 7.0, optimum reaction temperature 50℃. During activity measurement, the β-Galactosidase powder is dissolved in 100mM pH 7.3 potassium phosphate buffer solution to form a transparent liquid. β-galactosidase can hydrolyze the galactose residues attached to monosaccharides, oligosaccharides or glycopeptides through β-1→4 glycosidic bonds; hence, β-Galactosidase is mainly used in enzyme-linked immunosorbent assays, coupled to antibodies as a marker. In addition, β-galactosidase can be used for sugar structure analysis, lactose detection, and sodium ion detection.

References:

[1] Valieva Y, Ivanova E, Fayzullin A, et al. Senescence-associated β-galactosidase detection in pathology[J]. Diagnostics, 2022, 12(10): 2309.

[2] Lu L, Guo L, Wang K, et al. β-Galactosidases: A great tool for synthesizing galactose-containing carbohydrates[J]. Biotechnology advances, 2020, 39: 107465.

[3] Feng B, Chu F, Bi A, et al. Fidelity-oriented fluorescence imaging probes for beta-galactosidase: From accurate diagnosis to precise treatment[J]. Biotechnology Advances, 2023, 68: 108244.

[4] Vera C, Guerrero C, Aburto C, et al. Conventional and non-conventional applications of β-galactosidases[J]. Biochimica et Biophysica Acta (BBA)-proteins and proteomics, 2020, 1868(1): 140271.