“…A region of about 250 amino acid residues located to the C-terminal end of bacterial modules that are involved in adding the last amino acid to the linear peptides (Figure and , pink color in following modules: ACV-Val, GrsB-Leu, SrfA-C-Leu, TycC-Leu, and BacC-Asn) exhibits homology to thioesterases. ,− ,,,, This region is referred to as the thioesterase domain (TE domain). It has been found in the same location in the bacterial operons encoding multifunctional enzymes for the synthesis of the ACV tripeptide, ,,, bacitracin, enterobactin, gramicidin S, pyoverdine, surfactin, and tyrocidine 41 which are of bacterial and fungal origin. Due to its location, it is tempting to speculate that the TE domain is involved in hydrolytic cleavage of the linear peptide products, i.e., termination of nonribosomal peptide biosynthesis.…”