In molecular biology, Glycoside hydrolase family 18 is a family

Protein family

A protein family is a group of evolutionarily-related proteins, and is often nearly synonymous with gene family. The term protein family should not be confused with family as it is used in taxonomy....

 of glycoside hydrolases

Glycoside hydrolase

Glycoside hydrolases catalyze the hydrolysis of the glycosidic linkage to release smaller sugars...

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Glycoside hydrolases  are a widespread group of enzymes that hydrolyse the glycosidic bond

Glycosidic bond

In chemistry, a glycosidic bond is a type of covalent bond that joins a carbohydrate molecule to another group, which may or may not be another carbohydrate....

 between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycoside hydrolases, based on sequence similarity, has led to the definition of >100 different families. This classification is available on the CAZy(http://www.cazy.org/GH1.html) web site, and also discussed at CAZypedia, an online encyclopedia of carbohydrate active enzymes.

Some members of this family, CAZY GH_18, belong to the chitinase

Chitinase

Chitinases are hydrolytic enzymes that break down glycosidic bonds in chitin. As chitin is a component of the cell walls of fungi and exoskeletal elements of some animals , chitinases are generally found in organisms that either need to reshape their own chitin or dissolve and digest the chitin of...

 class II group which includes chitinase, chitodextrinase and the killer toxin of Kluyveromyces lactis

Kluyveromyces lactis

Kluyveromyces lactis is a Kluyveromyces yeast commonly used for genetic studies and industrial applications. Its name comes from the ability to assimilate lactose and convert it into lactic acid.- Use :...

. The chitinases hydrolyse chitin

Chitin

Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world...

 oligosaccharides. The family also includes various glycoproteins from mammals; cartilage

Cartilage

Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

 glycoprotein and the oviduct

Oviduct

In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...

-specific glycoproteins are two examples.