What does epimerase mean?
An epimerase is a specialised enzyme that converts a molecule into one of its epimers — compounds with identical chemical formulas that differ in the spatial configuration of atoms at exactly one stereogenic centre. By rearranging the orientation of a single hydroxyl group on a sugar, for instance, an epimerase can transform glucose derivatives into galactose derivatives without altering the underlying molecular framework. Epimerases form part of the broader isomerase class of enzymes, since their reactions involve rearrangement rather than the addition or removal of atoms. They are best known from carbohydrate metabolism: the enzyme UDP-glucose 4-epimerase is indispensable to the Leloir pathway, which allows the body to utilise dietary galactose, and inherited defects in such enzymes can cause rare metabolic disorders. The term belongs strictly to scientific register, appearing in biochemistry textbooks, research literature, and clinical discussions of enzyme deficiencies rather than in everyday language.
nounAn epimerase is an enzyme that catalyses the conversion of one epimer into another — that is, it reversibly changes the configuration at a single stereocentre in a molecule, most commonly a sugar. Epimerases belong to the isomerase class of enzymes.
- An enzyme that catalyses the interconversion of epimers, differing in configuration at only one asymmetric carbon atom; classified among the isomerases.
"The enzyme UDP-glucose 4-epimerase interconverts glucose and galactose derivatives, a step essential for normal galactose metabolism."
"UDP-galactose 4-epimerase plays a central role in the Leloir pathway of galactose metabolism."
"Deficiency of this epimerase can result in a rare form of galactosaemia."
Regular plural; used when referring to multiple such enzymes or members of the class.
"Several epimerases participate in bacterial cell-wall synthesis."
Flip just one carbon atom's configuration and glucose becomes galactose — and it's an epimerase that does the flipping inside your cells.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of epimerase
The word 'epimerase' combines the Greek-derived element 'epi-', meaning 'upon' or 'beside', with 'meros', meaning 'part', reflecting the term 'epimer' coined by Emil Fischer in the late nineteenth century for sugars differing at a single asymmetric carbon. The suffix '-ase' was introduced in the late nineteenth century as the standard ending for enzyme names. The word thus arose within the German and English biochemical tradition of the early twentieth century as enzymology formalised its nomenclature.
How epimerase is actually used
A technical term confined to biochemistry and enzymology; not used in everyday speech. In formal writing it is typically paired with its substrate or cofactor prefix, as in 'UDP-glucose 4-epimerase'.
Easily confused with epimerase
An anomerase converts between anomers (differing at the anomeric carbon of a sugar), whereas an epimerase converts between epimers, which differ at any single stereocentre other than the anomeric carbon.