2. Prefix. (chemistry) isomeric; especially, of amino acids having two chiral centres, the second diastereoisomer to be discovered or synthesized ¹
¹ Source: wiktionary.com
Medical Definition of Allo-
1. 1. Other; differing from the normal or usual. 2. Chemical prefix formerly used with amino acids whenever their side chain contained an asymmetric carbon; for example, the alloisoleucines and allothreonines. Origin: G. Allos, other (05 Mar 2000)