Nicholas Sumesh
Dept. of Physics, Indian Institute of Science, Bangalore 560012, India.
Acta Crystallogr E Crystallogr Commun. 2015 Feb 28;71(Pt 3):o216-7. doi: 10.1107/S205698901500393X. eCollection 2015 Mar 1.
The title tripeptide, C17H23N3O6, contains a nonproteinogenic C-terminal amino acid residue, norvaline, which is an isomer of the amino acid valine. Norvaline, unlike valine, has an unbranched side chain. The mol-ecule has a Gly-Gly segment which adopts an extended conformation. The norvaline residue also adopts an extended backbone conformation while its side chain has a g (+) t conformation. In the crystal lattice, N-H⋯O and O-H⋯O hydrogen bonds stabilize the packing. Mol-ecules translated along the crystallographic a axis associate through an N-H⋯O hydrogen bond. The remaining three hydrogen bonds are between mol-ecules related by a 2 1 screw axis.
标题三肽C17H23N3O6含有一个非蛋白质ogenic C末端氨基酸残基正缬氨酸，它是氨基酸缬氨酸的异构体。与缬氨酸不同，正缬氨酸具有无支链的侧链。该分子有一个采用伸展构象的甘氨酸-甘氨酸片段。正缬氨酸残基也采用伸展的主链构象，而其侧链具有g(+)t构象。在晶格中，N-H⋯O和O-H⋯O氢键稳定堆积。沿晶轴a平移的分子通过N-H⋯O氢键缔合。其余三个氢键存在于由2 1螺旋轴相关的分子之间。
