Biomedical Engineering Reference
In-Depth Information
during pectin degradation), other monomeric sugars also induce the
expression of specifi c sets of genes. An endogalactanase-encoding gene
( galA ) and a β-galactosidase-encoding gene ( lacA ) from A. niger (de Vries
and Visser 2001) are expressed in the presence of arabinose and arabitol.
CONCLUSION
β-Galactosidase is one of the most commonly used industrial enzymes
due to a variety of suitable applications in the food and dairy sectors.
b-Galactosidase catalyzes the hydrolysis of β-1,4-galactosyl linkages
(also β-1,2, β-1,3 and β-1,6-linkages in many cases), removing b-linked
galactose residues from a range of substrates including plant derived oligo-
and polysaccharides, galactose-containing glycoproteins and lactose.
β-Galactosidases also cleave synthetic substrates, such as 4-nitrophenol-
β-D-galactose (4NP-β-Gal) and 2-nitrophenol-β-D-galactose (2NP-β-Gal).
Additionally β-galactosidase displays transglycosylation activity lending
the enzyme to enormous potential for synthesis of novel oligosaccharides
in food, pharmaceutical and medical applications.
Glycosidases are distributed widely in nature, in plants, animals and
in microorganisms. However, the source of the enzyme is often important
when considering biotechnological applications. Microorganisms have
the advantage of being capable of high levels of enzyme production.
Enzymes from fungal sources are often preferred due to their extracellular
localization, acidic pH optima and broad stability profiles. Many of
these enzymes are also glycosylated and are therefore more resistant to
hydrolysis by proteases. Several fungi have been approved for use in the
food and pharmaceutical industries. By obtaining information regarding
regulation of the expression of β-galactosidase, or through manipulation of
key regulatory elements in the promoter of the gene, expression levels of
the native enzyme may be increased or enhanced which would be of great
benefi t to biotechnological applications.
ACKNOWLEDGEMENTS
This chapter has been reviewed by Dr. Alan Hernon, Centre of
Sustainability, Institute of Technology Sligo, Ash Lane, Sligo, Ireland.
References
Ali, Z.M., S. Armugam and H. Lazan. 1995. β-Galactosidase and its signifi cance
in ripening mango fruit. Phytochemistry. 38: 1109-1014.
Search WWH ::




Custom Search