Anomer

In carbohydrate chemistry, a pair of anomers (from Greek ἄνω 'up, above' and μέρος 'part') is a pair of near-identical stereoisomers or diastereomers that differ at only the anomeric carbon, the carbon atom that bears the aldehyde or ketone functional group in the sugar's open-chain form.

For reducing sugars, anomerization is referred to as mutarotation and occurs readily in solution and is catalyzed by acid and base.

This reversible process typically leads to an anomeric mixture in which eventually an equilibrium is reached between the two single anomers.

For example, regardless of the configuration of the starting D-glucose, a solution will gradually move towards being a mixture of approximately 64% β-D-glucopyranoside and 36% of α-D-glucopyranose.

One of the most important physical properties that is used to study anomers is the specific rotation, which can be monitored by polarimetry.