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Figure 4
Hydrogen bonds in (a) the crystal structure of (I)[link] and (b) the crystal structure of L-Leu-L-Val 2-propanol solvate (Görbitz & Torgersen, 1999BB10; CSD refcode JUCSEF01). Peptide Cβ atoms and solvent C atoms carrying hydroxyl groups are shown as small spheres, other side-chain and solvent atoms have been omitted for clarity. The archetype S5 pattern in (b) is characterized by the presence of one syn and one anti head-to-tail C(8) chain with alternating mol­ecules being related by Screw symmetry (light grey shades), as well as a C(5) chain involving an amide >N—H donor and a carboxyl­ate acceptor. An S4 pattern has the same symmetry, but a C(4) chain to O=C< carbonyl acceptor, while consecutive mol­ecules in T5 and T4 sheets are related by Translation rather than by a screw operation (Görbitz, 2010BB6). See text for details on the red and blue shades.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 72| Part 5| May 2016| Pages 635-638
doi:10.1107/S2056989016005302
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