ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
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, α = 101.17(4)°, β = 97.22(4)°, γ = 89.80(3)°, Z = 1, R = 5.95% for 3018 data with |F0| 〉 3α(F), resolution 0.93 Å. The use of the torsion angle κ = C(i - 1)N(i)Cα(i)Cβ(i), where κ = 68° for D-Phe and κ = 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. © 1993 John Wiley & Sons, Inc.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360330308
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