Eurystatins A and B, new prolyl endopeptidase inhibitors. II. Physico-chemical properties and structure determination

The structures of eurystatins A and B, new prolyl endopeptidase inhibitors, have been elucidated by chemical degradation and spectral studies. They have in common a unique 13-membered cyclic peptide core composed of L-leucine, L-ornithine and (S)-3-amino-2-oxobutyric acid, and differ from each other in the alpha,beta-unsaturated fatty acid attached to the alpha-amino moiety of the ornithine.