Epimeric

In organic chemistry, 'epimeric' describes stereoisomers that differ in the configuration at only *one* chiral center (also called an asymmetric carbon) within a molecule possessing two or more chiral centers. These molecules are not mirror images of each other (unlike enantiomers) and therefore, are diastereomers. Epimers exhibit different physical and chemical properties at that specific chiral center where the configuration changes, but their other characteristics may be similar due to the rest of the molecular structure remaining the same. The term is most frequently used when discussing monosaccharides like glucose and galactose.

Epimeric meaning with examples

• Glucose and galactose are epimers; they only differ in the configuration at carbon 4. This subtle difference leads to distinct metabolic pathways and properties in biological systems. Glucose is a vital energy source, while galactose is found in lactose, a sugar in milk, and its conversion to glucose is crucial for energy.
• Mannose is an epimer of glucose, specifically at carbon 2. Though subtle, the difference influences enzymatic reactions, and the body metabolizes each sugar differently. Mannose is found in some fruits and supplements, and it interacts with certain cellular receptors, potentially affecting immune function and cellular adhesion.
• The synthesis of a desired carbohydrate often requires creating an epimeric center through specific reaction conditions. Careful control over the reaction pathway ensures that the desired epimer, and not its counterpart, is predominantly formed. Chemists use protecting groups and stereoselective reagents to control stereochemistry during the synthetic process.
• During enzymatic reactions, epimerization is a potential process, where an enzyme can interconvert epimers through a complex mechanism. This may be useful in metabolic pathways, and allows an organism to adjust the availability of different sugar epimers according to its demands.