Lactase

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Lactase
Identifiers
Symbol	LCT LAC; LPH; LPH1
HUGO	6530
Entrez	3938
OMIM	603202
RefSeq	NM_002299
UniProt	P09848
Other data
EC number	3.2.1.108
Locus	Chr. 2 q21

Lactase (LCT), a member of the β-galactosidase family of enzymes, is a glycoside hydrolase involved in the hydrolysis of the disaccharide lactose into constituent galactose and glucose monomers. In humans, lactase is present predominantly along the brush border membrane of the differentiated enterocytes lining the villi of the small intestine.

Lactase is essential for digestive hydrolysis of lactose in milk. Deficiency of the enzyme causes lactose intolerance; most humans become lactose intolerant as adults.^{[citation needed]}

Contents 1 Characteristics 2 Industrial use 3 External links 4 References

[edit] Characteristics

Lactase has an optimum temperature of about 48°C (118.4°F) for its activity and an optimum pH of 6.5.

[edit] Industrial use

Lactase produced commercially can be extracted both from yeasts such as Kluyveromyces fragilis and Kluyveromyces lactis and from fungi, such as Aspergillus niger and Aspergillus oryzae.^[1] Its primary commercial use is to break down lactose in milk to make it suitable for people with lactose intolerance. Lactase is also used in the manufacture of ice cream. Because glucose and galactose are sweeter than lactose, lactase produces a more pleasant taste. Lactose also crystallises at the low temperatures of ice cream; however, its constituent products stay liquid and contribute to a smoother texture. Lactase is used in the conversion of whey into syrup.

Lactase is also used to screen for blue white colonies into the MCS of various plasmid vectors in E.Coli or other bacteria.

[edit] External links

• E. coli β-galactosidase: PDB 1JYY
• The use of lactases in the dairy industry

[edit] References

1. ^ Seyis I, Aksoz N. Production of lactase by Trichoderma sp.. Food Technol Biotechnol 2004;42:121–124. Free text.