STRUCTURE AND BIOSYNTHESIS OF TOXINS FROM BLUE-GREEN-ALGAE (CYANOBACTERIA)

Microcystis and Nodularia species produce cyclic hepta- and pentapepti des, microcystins and nodularin, respectively, both containing the sam e unusual C20 amino acid, abbreviated Adda. Biosynthesis of nodularin from Nodularia and especially of Adda employs a pathway similar to tha t employed by Microcystis for producting microcystins. Nearly 30 new m icrocystins have been isolated in our laboratory from cyanobacteria sp ecies and their structures assigned, largely employing tandem FAB mass spectrometry (FABMS/CID/MS). Acyclic peptides, some of them presumed precursors of nodularin and microcystins, have now been isolated and c haracterized. The numerous analogs identified or synthesized allow the identification of important parameters in a structure-activity relati onship study.