Octapeptide cyclo- -

Patch-clamp experiments with the tubules of the similar octapeptide cyclo-[(Trp-D-Leu)3-Gln-D-Leu] in phospholipid bilayers indicate short-lived... 

Bitter, off-tasting, cyclopeptides can also arise during the storage of cold pressed vegetable oils. For example, fresh linseed oil provides a nutty flavour, but on storage at room temperature it develops a bitter off-taste. The key bitter compound responsible for the bitter taste is the cychc octapeptide cyclo-(Pro-Leu-Phe-Ile-MetO-Leu-Val-Phe), known as cyclolinopeptide E, which contains methionine sulfoxide. 

Gramicidin-S, cyclo[(Orn-Leu-D-Phe-Pro-Val)2], is a C2-symmetric, antibacterial, cyclic decapeptide. Structural studies have shown that the peptide conformation consists of two type IP p-turns with a connecting p-sheet. Based on molecular modeling studies and the results from earlier experimental studies of cyclic octapeptides, Ripka et al. at DuPont Merck Pharmaceuticals believed that the four amino acids that make up one of the p-turns could be replaced by a benzodiazepine (BZD) moiety. These authors designed the gramicidin-S analogue cyclo(Lys-Leu-D-Phe-Pro-Val-Lys-BZD) (95) based on... 

---