Volume 36, Issue 5 pp. 659-667
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Conformational studies of retro–inverso peptides: The crystal and molecular structure of the hydantoin from H-Ala-G-Ala-mGly-OBzl

Ettore Benedetti

Ettore Benedetti

Biocrystallography Research Center, CNR Department of Chemistry University of Naples “Federico II” 80134 Naples, Italy

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Emilia M Pedone

Emilia M Pedone

Biocrystallography Research Center, CNR Department of Chemistry University of Naples “Federico II” 80134 Naples, Italy

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Noriyuki H Kawahata

Noriyuki H Kawahata

Department of Chemistry and Biochemistry University of California San Diego, La Jolla, CA 92093

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Murray Goodman

Murray Goodman

Department of Chemistry and Biochemistry University of California San Diego, La Jolla, CA 92093

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First published: November 1995
Citations: 10

Abstract

The crystal structure of the hydantoin 1-[(S)-1′–aminoethylmalonyl benzyl ester]-(S)-4-methylimidazolidin-2.5-dione (1) derived from the peptide H-Ala-gAla-mGly-OBzl, Having the retro-inverso modification of the Ala-Gly bond, has been determined by x-ray diffraction analysis. The crystals are orthorhombic, space group P212121 with a = 6.539. b = 14.721, c = 17.101 Å, z = 4. The structure was solved by direct methods and refined with anisotropic thermal factors to a final R value of 0.067 for the 947 observed reflections.

Reversal of the Ala-Gly amide bond perturbs the folding tendency of the backbone shown by the parent peptide t-BuCO-Ala-Gly-NHiPr. The gem-diamino residue, gAla, and the malonyl moieties are found in the helical and the extended conformations, respectively. Intramolecular hydrogen bonding is not observed. The molecules in the crystal are held together by the formation of two intermolecular hydrogen bonds of the NHOC type with NO distances of 2.86 and 3.17 Å respectively. 1995 John Wiley&Sons. Inc. © 1995 John Wiley & Sons, Inc.

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