## Abstract The Ο angle in a cyclic peptide is determined by the combined use of homonuclear and heteronuclear coupling constants. Two of the four coupling constants that define the Ο angle in a peptide are determined exactly, two qualitatively. Via Karplusβtype equations, they are transformed into
Conformation of peptide T in aqueous solution. Determination of homonuclear coupling constants by selective HOHAHA techniques
β Scribed by Klaus Zangger; Heinz Sterk
- Book ID
- 102528858
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 412 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0749-1581
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β¦ Synopsis
Abstract
The conformation of Peptide T in aqueous solution was investigated by means of ^1^H NMR spectroscopy in one and two dimensions. The data were compared with those obtained previously for the peptide in DMSO solution. While Peptide T forms a Ξ²βturn in DMSO, no evidence was found for such a structure in water. Instead, Peptide T exists in aqueous medium in a random coil conformation with an increased tendency to form a stretched chain at the ends of the peptide backbone. This partly populated Ξ²βstrand was identified mostly by the analysis of atomic distances and coupling constants. To evaluate NMR parameters such as chemical shift and scalar coupling constants in the heavily overcrowded spectral regions, selective homonuclear HartmannβHahn transfer was employed, which allows the observation of a distinct multiplet through the excitation of its scalar coupling partner, and subsequent magnetization transfer.
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