ABSTRACT
Most organic molecules in living organisms contain asymmetrical centers (i.e., they are chiral). (The terminology of stereochemistry has been reviewed by Moss.1) For example, amino acids that are incorporated into proteins are l and sugars in carbohydrates are d. It is understandable that the three-dimensional structures of the receptors in proteins for small molecules will favor only one optical isomer (i.e., the one that ts sterically, hydrogen bonds properly, and so on). Most compounds made for use by plants and animals will have to be single optical isomers. These include agricultural chemicals, drugs, avors, food additives, fragrances, and such. This is especially important with drugs,2 for which the unwanted isomer may produce toxic side effects.
