STUDIES ON THE SOLUTION-STATE AND SOLID-STATE STRUCTURE OF PATELLIN-2

The major component of a new family of novel cyclic peptides has been characterized from the Fijian marine tunicate (ascidian) Lissoclinum patella (Gottschaldt, 1898). Patellin 2 (4) lacks the characteristic thiazole and oxazoline amino acids present in the previously reported Lissoclinum peptides and contains a thiazoline and two threonine residues modified as dimethylallyl ethers. Patellin 2 is shown to exist in different conformations in solution and in the crystal on the basis of X-ray crystallography, NMR spectroscopy, and molecular modeling. Cis-trans isomerization of the Val-Pro amide bond leads to two distinct conformers in solution, while the crystalline conformers (with the more stable trans-Val-Pro amide bond) differ by inversion of the thiazoline ring. © 1990, American Chemical Society. All rights reserved.