sentence: LarD might be able to recognize the subtle difference between glutamic acid and aspartic acid to make the macrolactam ring by condensation between a α - amino group of glycine at N terminal and a γ - carboxylic acid of glutamic acid residue at the position 8. Similarly , replacement studies of microcinJ25 ( E8D ) 31 , capistruin ( D9E ) 32 , astexin-1 ( D9E ) 10 , caulosegnin I ( E8D ) 33 and xanthomonin II ( E7D ) 34 were reported , but the production of D9E variant in astexin-1 only was confirmed with low production amount .