{{Short description|Class of chemical compounds}} A '''galactoside''' is a glycoside containing galactose. The H of the OH group on carbon-1 of galactose is replaced by an organic moiety.<ref>{{Cite book|url=https://books.google.com/books?id=B4wtDAAAQBAJ&dq=A+galactoside+is+a+glycoside+containing+galactose&pg=PA738|title=Mosby's Medical Dictionary - E-Book|isbn=9780323414265|author1=Mosby|date=29 April 2016|publisher=Elsevier Health Sciences }}</ref> [[File:ONPG structure.png|thumb|224x224px|Structure of ONPG, an example of a β-galactoside.]] Depending on whether the glycosidic bond lies "above" or "below" the plane of the galactose molecule, galactosides are classified as α-galactosides or β-galactosides.
A β-galactoside is a type of galactoside in which the glycosidic bond lies above the plane of the galactose residue. The most commonly recognized and used β-galactoside in biochemistry is lactose.{{Citation needed|reason=lactose is not a glycoside because it is made ot sugar + sugar instead of sugar + another organic compound (not sugar)|date=August 2022}} However, other chemicals, such as ONPG, are known, but these are typically synthesized for biochemical assays.
Galactosides play significant roles in metabolic processes of many organisms and are hydrolyzed by a class of enzymes called galactosidases and are classified according to what type of glycosidic linkage on the galactoside they will break.<ref name=":0">{{Citation |last=Huber |first=R. E. |title=Beta (β)-Galactosidase |date=2001-01-01 |url=https://www.sciencedirect.com/science/article/pii/B0122270800004894 |encyclopedia=Encyclopedia of Genetics |pages=212–214 |editor-last=Brenner |editor-first=Sydney |place=New York |publisher=Academic Press |language=en |isbn=978-0-12-227080-2 |access-date=2022-05-12 |editor2-last=Miller |editor2-first=Jefferey H.}}</ref> For example, enzymes that hydrolyze the β-galactoside glycosidic bond are called β-galactosidases, while those that hydrolyze the α-galactoside glycosidic bond are known as α-galactosidases.<ref name=":0" />
==References== {{Reflist}}
{{Glycosides}}
Category:Galactosides