Redetermined crystal structure of α-dl-me-thio-nine at 340 K.

ABSTRACT: Two forms, α and β, are known for the racemic amino acid dl-me-thio-nine, C5H11NO2S. The phase transition between them, taking place around 326 K, is associated with sliding at the central inter-faces of the hydro-phobic regions in the crystal, leaving the hydrogen-bonding pattern unperturbed. For the high-temperature α phase, only a structure of rather low quality has been available [R factor = 0.118, no H-atom coordinates; Taniguchi et al. (1980 ▶). Bull. Chem. Soc. Jpn, 53, 803-804]. We here present accurate structural data for this polymorph [R(F) = 0.049], which are compared with other related amino acid structures with similar properties. We report for the first time that the side chain of this phase has a minor disorder component [occupancy 0.0491 (18)] with a gauche+ rather than a

SUBMITTER: Gorbitz CH 

PROVIDER: S-EPMC4257343 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature