enantiomère

Enantiomers are a pair of molecules that are non-superimposable mirror images of each other, much like a left and right hand. This stereochemical relationship means they have the same chemical formula and connectivity of atoms but differ in their three-dimensional arrangement. A defining characteristic of enantiomers is their optical activity. When plane-polarized light passes through a solution of a chiral compound, enantiomers will rotate the light in opposite directions. One enantiomer will rotate the light clockwise (designated as dextrorotatory or +), while the other will rotate it counterclockwise (designated as levorotatory or -). A mixture containing equal amounts of both enantiomers is called a racemic mixture or racemate, and it is optically inactive because the rotations cancel each other out. Chirality, the property that leads to enantiomers, is prevalent in biological systems. Many biologically active molecules, such as amino acids and sugars, are chiral. The different spatial arrangements of enantiomers can lead to vastly different biological effects, as receptors and enzymes in the body are often stereoselective, meaning they interact preferentially with one enantiomer over the other. This selectivity is crucial in pharmacology, where the efficacy and side effects of drugs can depend on which enantiomer is administered.