Conformational studies of Angiotensin II and analogues in dimethyl sulfoxide by 1H NMR: Lability and intramolecular interactions of the tyrosine hydroxyl and histidine imidazole NH protons

Autor:	Raghav Yamdagni, Graham J. Moore, Glen Bigam, John Matsoukas
Rok vydání:	1991
Předmět:	chemistry.chemical_compound chemistry Stereochemistry Intramolecular force Proton NMR Imidazole Peptide bond General Chemistry Nuclear magnetic resonance spectroscopy Nuclear Overhauser effect Angiotensin II Histidine
Zdroj:	Collection of Czechoslovak Chemical Communications. 56:1348-1357
ISSN:	1212-6950 0010-0765
DOI:	10.1135/cccc19911348
Popis:	1H NMR studies in dimethyl sulfoxide illustrate that the tyrosine hydroxyl proton and the histidine imidazole NH proton in [Sar1]ANGII and analogues are labile at neutral pH but not at acid pH. This is attributable to intramolecular interactions of these groups with negatively charged groups. Methylation or elimination of the Tyr hydroxyl in [Sar1]ANGII and analogues, invokes a small but consistent deshielding effect on the His C-2 and C-4 protons, suggesting an interaction between the Tyr hydroxyl and the His ring. Nuclear Overhauser Effect (NOE) enhancement experiments in {Sar1]ANGII and the Sarmesin analogue [Des1, Tyr(Me)4]ANGII, support the Tyr/His interaction and confirm the presence of a trans His-Pro peptide bond.
Databáze:	OpenAIRE
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