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Conformational investigations on glycosylated threonine‐oligopeptides of increasing chain length
Author(s) -
Biondi Laura,
Filira Fernando,
Gobbo Marina,
Pavin Enrico,
Rocchi Raniero
Publication year - 1998
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/(sici)1099-1387(199802)4:1<58::aid-psc129>3.0.co;2-b
Subject(s) - chemistry , amide , solubility , peptide , chemical shift , acetylation , stereochemistry , crystallography , organic chemistry , biochemistry , gene
Stepwise solution syntheses are described of the homo‐oligomers Z‐(Thr) n ‐NHCH 3 ( n =1–4, I 1–4 ), Z‐{[Gal(Ac) 4 β]Thr} n ‐NHCH 3 ( n =1–5, II 1–5 ) and Z‐[(Galβ)Thr] n ‐NHCH 3 ( n =1−5, III 1–5 ). Members of the III 1–5 series were obtained by de‐acetylation of the corresponding oligomers of the II 1–5 series. The conformational preferences of the terminally protected homo‐peptides of the three series were investigated by FT‐IR absorption spectroscopy both in the solid state and in CDCl 3 solution, at various concentrations. Proton NMR measurements in CDCl 3 and in DMSO‐d 6 were also carried out and the effect of temperature variation on the chemical shifts of amide protons was determined in DMSO‐d 6 (range 298–335 K) and in CDCl 3 (range 298–320 K). CD spectra were recorded in water and in TFE. Solubility problems prevented measurements in CDCl 3 solution for Z‐(Thr) 4 ‐NHCH 3 and for the entire III 1–5 series. The existence of unordered structures in the carbohydrate‐free oligomers and of more or less extended, organized structures in the glycosylated derivatives is indicated by the NMR and IR measurements. The sugar moieties apparently show a structure‐inducing effect on the peptide chain. ©1998 European Peptide Society and John Wiley & Sons, Ltd.