title: Crystal structure of the tripeptide N-(benzyl-oxycarbon-yl)glycylglycyl-l-norvaline.
abstract: 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.
authors.affiliation: Dept. of Physics, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Sumesh
authors.initials: S
authors.lastname: Nicholas
keywords: conformation; crystal structure; glycine; hydrogen bonding; norvaline; peptide
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