Amino acid racemization dating
In general, most biochemical reactions are stereoselective, so only one stereoisomer will produce the intended product while the other simply does not participate or can cause side-effects.
Of note, the form of sugars (primarily glucose) are usually the biologically reactive form.
Kennedy (1980) Inter- and intra-generic trends in apparent racemization kinetics of amino acids in Quaternary mollusks. He was able to separate two enantiomer crystals that rotated polarized light in opposite directions. In Initial Reports, Deep Sea Drilling Program 9, 903-905. Enantiomers should also be distinguished from diastereomers which are a type of stereoisomer that have different molecular structures around a stereocenter and are not mirror images.Racemate may have different physical properties from either of the pure enantiomers because of the differential intermolecular interactions (see Biological Significance section).