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Indian Journal of Chemistry -Section B (IJC-B) >
IJC-B Vol.48B [2009] >
IJC-B Vol.48B(03) [March 2009] >
| Title: | N and N+1 cap effects of Gly, Ala, Leu, Val, Pro and Aib in Boc-(D)Glu₁-Xxx₂-Yyy₃-Lys₄-NHMe, a 3₁₀ type protohelix endlocked by Boc-(D)Glu |
| Authors: | Bobade, V D
Gaikwad, N D
Mhaske, P C |
| Keywords: | 3₁₀ Helix
II′ turn
Reverse turn
D amino acids
NMR studies |
| Issue Date: | Mar-2009 |
| Publisher: | CSIR |
| Abstract: | Gly, Ala, Leu, Val, Pro and Aib are introduced as N cap (Xxx₂) or N+1 cap (Yyy₃) residues in Boc-(D)Glu₁-Xxx₂- Yyy₃-Lys₄-NHMe, a 3₁₀ like protohelix endcapped by Boc-(D)Glu. NOEs, NH temperature coefficients and ³JNHCα coupling constants establish that all variants, except Boc-(D)Glu₁-Ala₂-Pro₃-Lys₄-NHMe, 1e are distorted 3₁₀ type protohelices, while the response of Glu₁ NH- a reporter of Lys₄→Glu₁ salt bridge-to solvent, salt and temperature induced perturbations, reveals that the protohelix variants differ appreciably in the degree of ordering and overall stability. The capping position variations are thus shown to affect the protohelix stability in a manner that is strongly reminiscent of the presumed effects in helix nucleation. |
| Page(s): | 386-396 |
| ISSN: | 0376-4699 |
| Source: | IJC-B Vol.48B(03) [March 2009]
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