Presence of pseudo-peptide bond in the crystal structure of n-(t-butoxycarbonyl)-꺯-n'-benzyloxycarbony-l-lysyl-l-isoleucine (boc-lys(obzl)-ile) by S. M. Malathy Sony, N. Sukumar, M. N. Ponnuswamy, and R. Jayakumar

Crystal Research and Technology

Cryst. Res. Technol. 39, 368 (2004) - Abstract -

Presence of pseudo-peptide bond in the crystal structure of n-(t-butoxycarbonyl)-꺯-n'-benzyloxycarbony-l-lysyl-l-isoleucine (boc-lys(obzl)-ile)

S. M. Malathy Sony, N. Sukumar, M. N. Ponnuswamy, and R. Jayakumar*

Department of Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai-600 025, India
*Bioinorganic Chemistry, Central Leather Research Institute, Adyar, Chennai-600 020, India

Keywords	lysine, isoleucine, pseudo peptide bond, crystal, dipeptide, hydrogen bonds
PACS	61.66.Hq
DOI	10.1002/crat.200310197

The dipeptide Boc-Lys(OBzl)-Ile crystallizes in monoclinic space group P2₁ with cell parameters a = 5.003(1), b = 19.199(3), c = 15.270(2)Å, β =93.42(1)줩, V = 1464.1(3)Å³, Z = 2, D_cal = 1.117 Mg/m³ at T = 293 K. The structure was solved by direct methods and refined by full-matrix least-squares procedure to a final R = 0.096 and wR = 0.101 using 1379 reflections. The peptide unit is in trans conformation and the molecule takes up an extended conformation. In the lysine side chain, delocalization of electrons and pseudo peptide bond formation is observed at the interaction site of benzyloxycarbonyl group. Both N-H...O and main chain C-H...O hydrogen bonds stabilize the molecules in the unit cell in a parallel β-sheet fashion.

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