Conversely, peptides p3 and 15c predominantly remained monomeric or low-oligomeric even at 1.5 mM, consistent with their fragmented hydrophobic surfaces and lower values of the molecular hydrophobicity potential (MHP) compared to parent peptide p1 (Figure ). Detailed analysis of the stability/flexibility of the backbone structure in these peptides indicated another substantial difference. Since the maximal distance between neighboring backbone H N atoms in a short cyclic peptide is almost always within the limits of NOE detectability (i.e. below 5.5 Å), the appearance of the NOE cross-peaks between them is rather defined by the structural stability of the backbone than the distances themselves. H N groups of the backbone lacking a preferred conformation are subject to variable chemical environments.