1. A prefix which indicates a shift by one position of all single and double bonds in a conjugated polyene system. GNOC Recom. R-1.2.7.2. It has been applied only to carotenoids (BNRD Rule Carotenoid-9, p. 229) and retinoids (BNRD, Rule Ret. 4.7, p.249). E.g. retro-carotenoids, retro-retinoids.
2. A prefix which indicates the reverse sequence of a peptide. BNRD, Nomenclature and symbolism for amino acids and peptides. Rule 3AA-22.7 (p. 64).
