ANALYSIS OF THE THERMAL TRANSITIONS OF A MODEL HELICAL PEPTIDE USING C-13 NMR

Citation
W. Shalongo et al., ANALYSIS OF THE THERMAL TRANSITIONS OF A MODEL HELICAL PEPTIDE USING C-13 NMR, Journal of the American Chemical Society, 116(6), 1994, pp. 2500-2507
Citations number
39
Categorie Soggetti
Chemistry
ISSN journal
00027863
Volume
116
Issue
6
Year of publication
1994
Pages
2500 - 2507
Database
ISI
SICI code
0002-7863(1994)116:6<2500:AOTTTO>2.0.ZU;2-D
Abstract
The thermal dependence of the C-13 reonances of individual residues in the model peptide, acetylW(EAAAR)3-Aamide, was analyzed in terms of a two-state transition. The correlation of the effects of temperature, pH, and salt concentration on C-13 NMR and circular dichroic measureme nts of this peptide suggest that both measurements observe a common tw o-state helix/coil transition. The thermodynamic parameters which char acterize the thermal transition of each residue suggest that the helic al conformation of the peptide is stabilized by hydrogen bonds and by burial of apolar surfaces and that the helical conformation melts as a largely cooperative unit. The terminal regions of the helix appear le ss frayed than expected from the Lifson-Roig statistical mechanical mo del for a peptide helix/coil transition, indicating contributions from stabilizing noncovalent interactions in addition to backbone hydrogen bonds.