These peptides are synthesized using a modular enzyme complex, because why take the easy route when you can build an intricate, customizable factory? Non-ribosomal peptides are confined primarily to unicellular organisms, plants, and fungi, where they apparently enjoy their exclusive little club. There is a common core structure to all of these complexes, but don’t let that fool you—these bad boys can contain many different modules to perform chemical manipulations on the evolving product, like a biochemical Swiss army knife.
In general, these peptides are cyclic, often boasting highly-complex cyclic structures that would make even the most seasoned chemist’s head spin. But because non-ribosomal peptides love keeping us on our toes, linear nonribosomal peptides are also fairly common, just to remind us that they can play by any rules they want.
So, in essence, non-ribosomal peptides are the molecular mavericks, doing things their own way and looking pretty stylish while they’re at it.