Nature makes many macrocycles with diverse structures and functions.
We have studied the enzyme mechanisms and protein structures associated with the production of the patellamides in detail within our laboratories. These are members of the family of ribosomally produced and post-translationally modified peptides (RiPPs) called the cyanobactins. The biosynthetic enzymes originate from a number of different freshwater and marine symbiotic or free living cyanobacteria (blue-green algae).
These macrocyclic peptides are defined by a C to N terminal peptide bond, the incorporation of heterocycles at different oxidation states (Thiazoline ThH, Oxazoline OxH, Thiazole Thz, Oxazole Oxz) and possible decoration with prenyl groups. Some cyanobactins incorporate inverted stereocentres at the C∝ adjacent to ThH/Thz.