Galactosidases sources

Qf-galactosidase was found in the early 20th century, but it has always existed in nature. The source of this enzyme is very wide, and exists in seeds and tissues of mammals, and many microorganisms can also produce a-galactosidase. Table 2.8 lists the various or-galactosidase source. 

Escherichia coli cells grown in a medium with lactose as the only carbon source are monitored for p-galactosidase activity over time with the results shown below. 

Sample quality is generally assessed by the determination of /J-galactosidase activity. For MPS type IVB, the a-mannosidase activity is chosen as an indicator enzyme. Leukocyte homogenates that are sufficient for at least 20 separate runs are prepared from one source and aliquots are kept frozen. These samples serve as quality controls for each run. Heat-inactivated leukocyte homogenates may serve as a positive control (patient-mimics). 

Lactose may be hydrolysed to glucose and galactose by enzymes (fi-galactosidases, commonly called lactase) or by adds. Commercial sources of / -galactosidase are moulds (especially Aspergillus spp.), the enzymes from which have acid pH optima, and yeasts (Kluyveromyces spp.) which produce enzymes with neutral pH optima. /S-Galactosidases were considered to have... 

Source and kinds of disaccharidases The final digestive processes occur at the mucosal lining of the small intestine. Several disaccharidases [for example, lactase (p-galactosidase), sucrase, maltase, and isomal-tase] produce monosaccharides (glucose, galactose, and fructose). These enzymes are secreted by and remain associated with the luminal side of the brush border membranes of intestinal mucosal cells. Absorption of the monosaccharides requires specific trans porters. 

A relatively more active source of melibiase is crude invertase from brewers yeast. Yeast melibiase is nearly free from /J-D-galactosidase, but it contains /3-D-mannosidase as well as /3-D-fructofuranosidase.23... 

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