Görbitz CH, Törnroos KW, Day GM. Single-crystal investigation of L-tryptophan with Z' = 16.
ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 2012;
68:549-57. [PMID:
22992800 DOI:
10.1107/s0108768112033484]
[Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 07/24/2012] [Indexed: 11/10/2022]
Abstract
A complex, disorder-free structure in the space group P1 has been established for L-tryptophan, for which no crystal structure has previously been available. The 16 molecules in the asymmetric unit can be divided into two groups of eight; one where the side chains have gauche orientations and one with trans orientations. Molecules within each group have almost identical molecular geometries. The unit-cell parameters mimic a hexagonal cell, but deviations from 90° for the cell angles α = 84.421 (4) and β = 87.694 (4)° give a small tilt that rules out hexagonal symmetry. The hydrogen-bonding pattern resembles that found in the crystal structure of the racemic structure of DL-tryptophan, but a lower density combined with longer hydrogen bonds and inter-aromatic interactions show that the enantiomeric structure is less efficiently packed.
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