15N NMR spectroscopy. 30—structure/shift relationships of oligopeptides and copolypeptides, including gramicidin S

摘要: The 15N NMR spectra of various oligopeptide derivatives the ZXYYOMe structure, where X and Y are variable amino acids Z is benzyloxycarbonyl group, were measured in several protic aprotic solvents. shift difference YY XY bond (neighbouring residue effect) discussed with respect to nature solvent. Oligopeptides ZXYYOH nH3XYYOMe structures compared Z-peptide esters investigate spectroscopic influence protecting groups. methyl ester hydrochlorides 25 most common water DMSO elucidate solvent dependence substituent effects. Moreover, Z-amino N-acetyl-amino acid establish whether effects depend on derivatives. In this connection assignments serine, threonine glycine signals silk proteins. Furthermore, copolypeptides by comparison oligo- homo-polypeptides discussed. Finally, it was demonstrated that intramolecular H bonds cause downfied shifts 7–10 ppm acceptor amide