Disaccharidases are

glycoside hydrolases Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (cel ...

, enzymes that break down certain types of sugars called

disaccharide A disaccharide (also called a double sugar or ''biose'') is the sugar formed when two monosaccharides are joined by glycosidic linkage. Like monosaccharides, disaccharides are simple sugars soluble in water. Three common examples are sucrose, la ...

s into simpler sugars called monosaccharides. In the human body, disaccharidases are made mostly in an area of the small intestine's wall called the

brush border A brush border (striated border or brush border membrane) is the microvilli-covered surface of simple cuboidal and simple columnar epithelium found in different parts of the body. Microvilli are approximately 100 nanometers in diameter and their ...

, making them members of the group of "brush border enzymes". A genetic defect in one of these enzymes will cause a disaccharide intolerance, such as

lactose intolerance Lactose intolerance is a common condition caused by a decreased ability to digest lactose, a sugar found in dairy products. Those affected vary in the amount of lactose they can tolerate before symptoms develop. Symptoms may include abdominal pai ...

or sucrose intolerance.

Examples of disaccharidases

Lactase Lactase is an enzyme produced by many organisms. It is located in the brush border of the small intestine of humans and other mammals. Lactase is essential to the complete digestion of whole milk; it breaks down lactose, a sugar which gives ...

(breaks down lactose into

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

and

galactose Galactose (, '' galacto-'' + ''-ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molecu ...

) *

Maltase Maltase (, ''alpha-glucosidase'', ''glucoinvertase'', ''glucosidosucrase'', ''maltase-glucoamylase'', ''alpha-glucopyranosidase'', ''glucosidoinvertase'', ''alpha-D-glucosidase'', ''alpha-glucoside hydrolase'', ''alpha-1,4-glucosidase'', ''alp ...

(breaks down maltose into 2

s) * Sucrase (breaks down sucrose into

and fructose) *

Trehalase The enzyme Trehalase is a glycoside hydrolase, produced by cells in the brush border of the small intestine, which catalyzes the conversion of trehalose to glucose. It is found in most animals. The non-reducing disaccharide trehalose (α-D-glucop ...

(breaks down

trehalose Trehalose (from Turkish '' tıgala'' – a sugar derived from insect cocoons + -ose) is a sugar consisting of two molecules of glucose. It is also known as mycose or tremalose. Some bacteria, fungi, plants and invertebrate animals synthesize it ...

into 2

s)
For a thorough scientific overview of small-intestinal disaccharidases, one can consult chapter 75 of OMMBID.

Charles Scriver Charles Robert Scriver (born November 7, 1930) is a Canadian pediatrician and biochemical geneticist. Scriver made many important contributions to our knowledge of inborn errors of metabolism. He led in establishing a nationwide newborn metabol ...

, Beaudet, A.L., Valle, D., Sly, W.S., Vogelstein, B., Childs, B., Kinzler, K.W. (Accessed 2007)
The Online Metabolic and Molecular Bases of Inherited Disease
New York: McGraw-Hill. - Summaries of 255 chapters, full text through many universities. There is also th
OMMBID blog
. For more online resources and references, see

inborn error of metabolism Inborn errors of metabolism form a large class of genetic diseases involving congenital disorders of enzyme activities. The majority are due to defects of single genes that code for enzymes that facilitate conversion of various substances ( substr ...

Examples of disaccharidases

References

Further reading