Coordination Chemistry of Cyclic Peptides: Possible Biological Functions of the Patellamides
Cyclic pseudo-peptides, derived from marine metabolites of the genus Lissoclinum bistratum and Lissoclinum patella have attracted scientific interest in the last two decades. Their structural properties and solution dynamics were analyzed in detail, elaborate synthetic procedures for the natural products and synthetic derivatives were developed, the biosynthetic pathways were studied and it now is possible to produce them biosynthetically. A major focus in the last decade was on their CuII – more recently also on the ZnII – coordination chemistry, as a number of studies have indicated that di-nuclear CuII and ZnII complexes of cyclic peptides may be involved in the ascidians’ metabolism. Recent in vitro studies indicate that the dicopper(II) complexes have phosphatase, carbonic anhydrase, lactamase and glycosidase activity. Intererstingly, first in vivo studies with a patellamide derivative with an appended fluorescence molecule indicate that CuII is coordinated to the patellamides in the prochloron cells.