Subramanian E, Parthasarathy R
Center for Crystallographic Research, Roswell Park Memorial Institute, Buffalo, New York.
Int J Pept Protein Res. 1989 May;33(5):345-7. doi: 10.1111/j.1399-3011.1989.tb00692.x.
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).
来自甲醇水溶液的三肽甘氨酰 - 甘氨酰 - 肌氨酸（C7H13N3O4）晶体为正交晶系，空间群为Pbcn，在294 K时晶胞参数为a = 8.279(1)，b = 9.229(4)，c = 24.447(5)Å，V = 1868.0 Å3，分子量M.W. = 203.2，Z = 8。利用CAD - 4数据（1171个大于或等于3σ的反射）解析并精修了晶体结构，最终R值为0.053。第一个肽键是反式且平面的，而甘氨酸和肌氨酸之间的第二个肽键是顺式且明显非平面的（ω = 7.4度）。肽主链在N端部分具有伸展构象，但在C端部分采用聚甘氨酸II型构象。主链扭转角为：ψ1 = -173.9，ω1 = -177.8，(φ2, ψ2) = (-178.8, -170.8)，ω2 = 7.4，(φ3, ψ3) = (-81.6, 165.6度)。
