Iqbal, M and Balaram, P (1981) Membrane Channel Forming Polypeptides. 270-MHz Proton Magnetic Resonance Studies of the Aggregation of the 11-21 Fragment of Suzukacillin in Organic Solvents. In: Biochemistry, 20 (25). pp. 7278-7284.
|
PDF
membrane.pdf Download (12MB) |
Abstract
270-MHz 1H NMR studies of the 11-21 suzukacillin fragment Boc-Gln-Aib-Leu-Aib-Gly-Leu-Aib-Val-Aib-Aib-OMe (11-G) and its analogue Boc-Ala-Aib-Leu-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib-OMe (11-A) have been carried out in $CD{Cl}_3$ and ${({CD}_3)}_2SO$. The NH chemical shifts and their temperature coefficients have been measured as a function of peptide concentration in both solvents. It is established that replacement of Gln by Ala is without effect on backbone conformation. Both peptides adopt highly folded $3_{10}$ helical conformations stabilized by seven intramolecular 4 \rightarrow 1 hydrogen bonds. Nonlinear temperature dependences are demonstrated for free NH groups in the Gln(1) peptide. Aggregation is mediated by intermolecular hydrogen bonds formed by solvent-exposed NH groups. A major role for the Gln side chain in peptide association is suggested by differences in the NMR behavior of the Gln(1) and Ala(1) peptides. For the Gln(1) peptide in $CD{Cl}_3$, the carboxamide side chain carbonyl group forms an intramolecular hydrogen bond to the peptide backbone, while the trans side chain NH shows evidence for intermolecular interactions. In ${({CD}_3)}_2SO$, the cis carboxamide NH is involved in intermolecular hydrogen bonding. The possible role of the central Gln residue in sta-bilizing aggregates of peptide channel formers is discussed, and a model for hexameric association is postulated.
Item Type: | Journal Article |
---|---|
Publication: | Biochemistry |
Publisher: | American Chemical Society |
Additional Information: | Copyright for this article belongs to American Chemical Society. |
Department/Centre: | Division of Biological Sciences > Molecular Biophysics Unit |
Date Deposited: | 01 Jun 2005 |
Last Modified: | 19 Sep 2010 04:19 |
URI: | http://eprints.iisc.ac.in/id/eprint/3264 |
Actions (login required)
View Item |