Retro-enantiomeric [gammaCONH]-achatin-I (gamma-reach)


Date: Oct.1999


This structer was produced by RasMol,
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ORTEP-III (Burnett, 1996) drawing is left.

We have tried the retro-enantiomeric (RE) modification to mimic the parent conformation by reversing sequence and using enantiomeric amino acids (Doi, M. et al., Life Sci., 56, 1557-1562, 1995) and it was applied for achatin-I (H-Gly-D-Phe-Ala-Asp-OH). Achatin-I was isolated from the ganglia of an African giant snail and is the first example of the endogenous neuropeptide having a D-amino acid (Kamatani, Y. et al., Biochem. Biophys. Res. Commun., 160, 1015-1020, 1989). A \b-turn conformation has been revealed for achatin-I (Kamatani et al., FEBS Lett., 276, 95-97, 1990).

In the chemical syntheses of the RE analogues of achatin-I, an additional trial was applied, where the linkage of a gamma-amide bond was made at the D-Asp^1^ residue. The RE-modified achatin-I (H-D-Asp-D-Ala-Phe-Gly-OH) and [gammaCONH]-RE-achatin-I (H-D-Asp-[gammaCONH]-D-Ala-Phe-Gly-OH; gamma-REACH) were subjected into crystallization, and crystals of the later peptide were obtained from a dimethylformamide-water solution.

Paper: beta-Turn structure of a retro-enantiomeric analogue of achatin-I, H-D-Asp-[gammaCONH]-D-Ala-L-Phe-Gly-OH
Mitsunobu Doi, Akiko Asano, Toshimasa Ishida, Hiroyuki Minakata & Kyosuke Nomoto
Acta Crystallogr., Sect.C, 55, 422-424 (1999)

X-Ray Data Summary
formulaC18 H24 N4 O7
weight 408.41
symmetry orthorhombic
space group P212121
Cell Crystal
a 16.517(3) Ang. description needle
b 23.533(5) Ang. colour Colorless
c 5.1124(6) Ang. size (mm) 0.66x0.12x0.12
alpha 90.0 deg. Dx (g/ml) 1.365
beta 90.0 deg. F(000) 864
gamma 90.0 deg. mu(CuKa) 0.897
volume 1987.2(6) Ang^3
Z 4
Diffrn measurementRefinementspace
device type Rigaku AFC5R/RU-200 Flack ?
decay -1.2 % parameters 266
index limit 0-h-19, -27-k-27, 0-L-5 restraints 0
theta (deg.) 3.27-64.61 R_factor_gt 0.0450
total reflections3910 include Friedel pairs wR_factor_gt 0.1046
reflections(obs) 3107 .gt. 2sigma(I) dela rho_max 0.299 e A^3
Structure delta rho_min -0.298 e A^3
solution SHELXL-97 shift/su_maxlt. 0.001
refinementSHELXL-97 Goodness of fit 1.134

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