 lantibiotics are 
 a family of antibacterial peptide natural products 
 characterized by the post - translational installation of the thioether - containing 
 amino acids lanthionine and methyllanthionine . until recently , only 
 a single naturally occurring stereochemical configuration for 
 each 
 of these cross - links was known . 
 the discovery of lantibiotics with 
 alternative lanthionine and methyllanthionine stereochemistry has 
 prompted an investigation of its importance to biological activity . 
 here , solid - supported chemical synthesis enabled the total synthesis 
 of the lantibiotic lacticin 481 and analogues containing cross - links 
 with non - native stereochemical configurations . 
 biological evaluation 
 revealed that these alterations abolished the antibacterial activity 
 in all of the analogues , revealing the critical importance of the 
 enzymatically installed stereochemistry for the biological activity 
 of lacticin 481 . 
Supplementary Material