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 and absolute configuration of the cyclic Di-amino acid peptide: Cyclo(L-HomoCySH-L-HomoCySH). Journal of Chemical Crystallography, 41 (9). pp. 1328-1334. ISSN 1074-1542 (Print), 1572-8854 (Online) (doi:10.1007/s10870-011-0098-3)

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Abstract

The cyclic di-amino acid peptide cyclo(l-homoCySH-l-homoCySH) [(3S, 6S)-3, 6-bis(2-sulfanylethyl) piperazine-2,5-dione, C8H14N2O2S2, crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 6.1509(2) Å, b = 18.0217(9) Å, c = 29.6166(14) Å, V = 3283.0(2) Å3, Z = 12 (3 molecules, A, B and C, per asymmetric unit), D c = 1.422 g cm−3 and a linear absorption coefficient of 0.464 mm−1. The crystal structure determination was carried out with MoKα X-ray data measured at 120(2) K. In the final refinement cycle the data/restraints/parameter ratios were 5595/0/385 and goodness-of-fit on F 2 = 1.084. Final R indices for [I > 2sigma(I)] were R1 = 0.0746, wR2 = 0.1356 and R indices (all data) R1 = 0.1092, wR2 = 0.1529. The largest electron density difference peak and hole were 0.526 and −0.445e Å−3. The DKP rings in all three molecules are essentially, and unusually, planar and the C=O oxygen atoms are co-planar with the ring in each case. Ring atom rms deviations, including the =O groups, are 0.0668, 0.0658 and 0.0656 Å in molecules A, B and C, respectively. Details of the molecular geometry are compared with the compound cyclo(Gly-Gly) (Degeilh R, Marsh RE Acta Cryst 12:1007, 1959) and in addition some cyclic di-amino acid peptides in which the DKP rings have more puckered boat conformations

Item Type:	Article
Uncontrolled Keywords:	cyclic di-amino acid peptide, cyclic dipeptides, x-ray crystal structure, absolute configuration, 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/7474

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