Molecular asymmetry, isomerism involving different spatial arrangements of the same groups ( e.g., androsterone and isoandrosterone, differing only in that one has a 3α-OH, the other a 3β-OH). SEE ALSO: stereoisomer, Le Bel-van't Hoff rule. SYN: stereochemical isomerism.
* * *
ster·eo·isom·er·ism (ster″e-o-i-somґər-iz-əm) [stereo- + isomerism] the relationship between two or more isomers that have the same structure (the same linkages between atoms) but different configurations (spatial arrangements) in contrast to constitutional isomerism in which the isomers have different structures. Stereoisomers are further classified into enantiomers, those having molecules that are mirror images of each other, and diastereomers, those that do not. An older classification used the subdivisions optical and geometric isomerism (q.v.), which did not include all forms of stereoisomerism. Called also configurational, stereochemical, or spatial isomerism. stereoisomeric adj
Stereoisomerism, exemplified by a pair of cis-trans diastereomers.
Medical dictionary. 2011.