Page "Chirality (chemistry)" Paragraph 17

An optical isomer can be named by the spatial configuration of its atoms.

The / system, not to be confused with the d-and l-system, see above, does this by relating the molecule to glyceraldehyde.

Glyceraldehyde is chiral itself, and its two isomers are labeled and ( typically typeset in small caps in published work ).

Certain chemical manipulations can be performed on glyceraldehyde without affecting its configuration, and its historical use for this purpose ( possibly combined with its convenience as one of the smallest commonly used chiral molecules ) has resulted in its use for nomenclature.

In this system, compounds are named by analogy to glyceraldehyde, which, in general, produces unambiguous designations, but is easiest to see in the small biomolecules similar to glyceraldehyde.

One example is the amino acid alanine, which has two optical isomers, and they are labeled according to which isomer of glyceraldehyde they come from.

On the other hand, glycine, the amino acid derived from glyceraldehyde, has no optical activity, as it is not chiral ( achiral ).

Alanine, however, is chiral.