Crystal structure and conformation of glycyl-glycyl-sarcosine.
Crystals of the tripeptide, glycyl-glycyl-sarcosine (C7H13N3O4) from aqueous methanol are orthorhombic, space group Pbcn with cell parameters at 294 K of a = 8.279(1), b = 9.229(4), c = 24.447(5)A, V = 1868.0 A3, M.W. = 203.2, and Z = 8. The crystal structure was solved and refined using CAD-4 data (1171 reflections greater than or equal to 3 sigma) to a final R-value of 0.053. The first peptide linkage is trans and planar whereas the second peptide link between Gly and sarcosine is cis and appreciably non-planar (w = 7.4 degrees). The peptide backbone has an extended conformation at the N-terminal part but adopts a polyglycine-II type of conformation at the C-terminal part. The backbone torsion angles are: psi 1 = -173.9, w1 = -177.8, (phi 2, psi 2) = (-178.8, -170.8), w2 = 7.4, (phi 3, psi 3) = (-81.6, 165.6 degrees).
Center for Crystallographic Research, Roswell Park Memorial Institute, Buffalo, New York.
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Subramanian
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Parthasarathy
D003461:Crystallography; D006860:Hydrogen Bonding; D009842:Oligopeptides / Q000032:analysis*; D011487:Protein Conformation
D009842:Oligopeptides; C060757:glycyl-glycyl-sarcosine