A Southern hybridization analysis revealed that the region homologous to Escherichia coli lacZ was present on the chromosomal DNAs of beta-galactosidase-positive Shigella strains, such as Shigella dysenteriae serovar 1 and Shigella sonnei strains, whereas this region was absent from chromosomal DNAs of beta-galactosidase-negative strains of Shigella flexneri and Shigella boydii. We found that t...

Enzymatic hydrolysis of lactose is accompanied by galactosyl transfer to other sugars, thereby producing oligosaccharides. These are hydrolyzed slowly, both in vitro and in vivo. They can be thought of as low molecular weight, non-viscous, water-soluble, dietary fibre. They are considered to be physiologically functional foods which promote the growth of bifidobacteria in the colon and a wide v...

The thermodynamics of the hydrolysis of lactose to glucose and galactose have been investigated using both high pressure liquid chromatography and heat-conduction microcalorimetry. The reaction was carried out over the temperature range 282-316 K and in 0.1 M sodium acetate buffer at a pH of 5.65 using the enzyme beta-galactosidase to catalyze the reaction. For the process lactose(aq) + H2O(liq...

In patients with deficient intestinal lactase activity there is decreased hydrolysis of ingested lactose into its constituent monosaccharides glucose and galactose, and abdominal distension, cramps, and diarrhoea may occur after the consumption of lactose-containing foods. Unhydrolysed lactose within the lumen of the small intestine has been shown to exert an osmotic effect and this can be demo...

Two β-galactosidases, β-gal I and β-gal II, from Bifidobacterium breve DSM 20213, which was isolated from the intestine of an infant, were overexpressed in Escherichia coli with co-expression of the chaperones GroEL/GroES, purified to electrophoretic homogeneity and biochemically characterized. Both β-gal I and β-gal II belong to glycoside hydrolase family 2 and are homodimers with native molec...