Mendham, Andrew P., Spencer, John, Chowdhry, Babur Z., Dines, Trevor J., Mujahid, Muhammad, Palmer, Rex A., Tizzard, Graham J. and Coles, Simon J. (2011) X-ray crystallographic structure of the cyclic di-amino acid peptide: N,N′-Diacetyl-cyclo(Gly-Gly). Journal of Chemical Crystallography, 41 (9). pp. 1323-1327. ISSN 1074-1542 (Print), 1572-8854 (Online) (doi:10.1007/s10870-011-0097-4)

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Abstract

The cyclic di-amino acid peptide N,N;-diacetylcyclo(Gly-Gly), C(8)H(10)N(2)O(4), crystallizes in the triclinic space group P (1) over bar with unit cell parameters a = 9.4855(4) angstrom, b = 10.0250(3) angstrom, c = 10.0763(4) angstrom, alpha = 73.682(2)degrees, beta = 82.816(2)degrees, gamma = 81.733(2)degrees, V = 906.40(6) angstrom(3), Z = 4 (2 molecules, A and B, per asymmetric unit), D(c) = 1.452 g cm(-3) and linear absorption coefficient 0.118 mm(-1). The crystal structure determination was carried out with MoK alpha X-ray data measured at 120(2) K. In the final refinement cycle the data/restraints/parameter ratios were 4124/0/258 and goodness-of-fit on F(2) = 1.0008. Final R indices for [I > 2 sigma(I)] were R(1) = 0.0501, wR(2) = 0.1007 and R indices (all data) R(1) = 0.0864, wR(2) = 0.11180. The largest electron density difference peak and hole were 0.241 and -0.232 e angstrom(-3), respectively. The DKP rings in both molecules A and B have boat conformations with pseudo mm2 (C(2v)) symmetry if the N atoms and CH(2) groups are considered identical. In each case, the prow and stern of the boat are the alpha-carbons C(3) and C(6). The overall molecular symmetry of molecules A and B is approximately C(2) with the twofold symmetry axis of the DKP boat being maintained through the centre of the DKP ring. Details of the molecular geometry are compared with that of the parent compound cyclo(Gly-Gly) in which the DKP ring is planar with exact symmetry (1) over bar (C(i)).

Item Type:	Article
Additional Information:	[1] Supplementary Material: Crystallographic data (excluding structure factors) for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC 799332. Copies of available material can be obtained, free of charge, via www.ccdc.cam.ac.uk/conts/retrieving.html or on application to the Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44(0)1223-336033 or e-mail: teched@chemcrys.cam.ac.uk).
Uncontrolled Keywords:	cyclic dipeptide, cyclic di-amino acid peptide, x-ray crystal structure, DKP ring conformations
Subjects:	Q Science > QD Chemistry
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > School of Science (SCI) Faculty of Education, Health & Human Sciences > School of Human Sciences (HUM)
Related URLs:	Publisher
Last Modified:	09 Oct 2021 04:46
URI:	http://gala.gre.ac.uk/id/eprint/7220

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