Karle, I. L. ; Flippen-Anderson, J. L. ; Uma, K. ; Balaram, P. (1993) Accommodation of a D-Phe residue into a right-handed 310-helix: Structure of Boc-D-Phe-(Aib)4-Gly-L-Leu-(Aib)2-Ome, an analogue of the amino terminal segment of antiamoebins and emerimicins Biopolymers, 33 (3). pp. 401-407. ISSN 0006-3525
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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/bip.360...
Related URL: http://dx.doi.org/10.1002/bip.360330308
Abstract
The crystal structure of the nonapeptide Boc-D-Phe-Aib-Aib-Aib-Aib-Gly-Leu-Aib-AibOMe (I), which is an analogue of the N-terminal sequence of antiamoebins and emerimicins, establishes a completely 310-helical conformation with seven successive intramolecular 4 →1 hydrogen bonds. The average, Φ, ψ values for residues 1-8 are -59° and -32°, respectively. Crystal parameters are C47H77N9O12, space group P1, a = 10.636(4) Å, b = 11.239(4) Å, c = 12.227(6) Å, = 101.17(4)°, β = 97.22(4)°, = 89.80(3)°, Z = 1, R = 5.95% for 3018 data with |F0| > 3 α(F), resolution 0.93 Å. The use of the torsion angle k = C(i - 1)N(i)Cα(i)Cβ(i), where k = 68° for D-Phe and k = 164° for L-Leu, confirms the opposite configurations of these residues. The Φ, ψ values of -62° and -32° at D-Phe are unusual, since this region is characteristic of residues with L configurations. Peptide I possesses only two chiral residues of opposing configuration. The observed right-handed 310-helical structure suggests that helix sense has probably been determined by the stereo-chemical preferences of the Leu residue.
Item Type: | Article |
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Source: | Copyright of this article belongs to John Wiley and Sons. |
ID Code: | 91404 |
Deposited On: | 21 May 2012 12:46 |
Last Modified: | 21 May 2012 12:46 |
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