Peptide—lanthanide cation equilibria in aqueous solution. III—Temperature dependence of l-carnosine-Ln3+ bound shifts. Isomorphous substitution and side-chain folding
✍ Scribed by J. C. Mossoyan; J. Ouarzazi; D. Benlian
- Publisher
- John Wiley and Sons
- Year
- 1987
- Tongue
- English
- Weight
- 493 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
The temperature dependence of paramagnetic shifts induced for proton resonances has been investigated for lanthanide (Dy, Ho and Yb) complexes of ccarnosine. Two different methods of data reduction were used to separate contact, pseudo-contact and diamagnetic contributions to the paramagnetic shift, one using induced bound shifts and the other based on temperature plots of the induced shift ratios. These studies revealed that diamagnetic effects, which include conformational changes, inductive effects and direct field effects, cannot be neglected. In the Dy, Ho and Yb complexes the side-chain is folded, but isomorphous replacement and axial symmetry are retained.