Tunicamycin 14:1 is a mixture of tunicamycin structural isomers that contain a 14-carbon N-acyl chain with variable branching patterns. The N-acyl chain incorporated into tunicamycins, like tunicamycin 14:1, is derived from the same pool of cellular branched-chain fatty acids (BCFAs) in Streptomyces and directly impacts the biological activity of each individual tunicamycin variant.1,2,3Purified tunicamycin 14:1 with the iso branching configuration inhibits bacterial phospho-MurNAc-pentapeptide transferase (MraY) with an IC50 value of 0.31 μM.2