Gebreslasie Hadgu Girmay, Jacobsen Øyvind, Görbitz Carl Henrik
Department of Chemistry, University of Oslo, PO Box 1033 Blindern, N-0315 Oslo, Norway.
Acta Crystallogr C. 2011 Sep;67(Pt 9):o359-63. doi: 10.1107/S0108270111029647. Epub 2011 Aug 6.
The title compound [systematic name (6S,12S)-methyl 6-(allyloxymethyl)-12-isopropyl-2,2,9,9-tetramethyl-4,7,10-trioxo-3-oxa-5,8,11-triazatridecan-13-oate], C(21)H(37)N(3)O(7), containing the little studied O-allyl-L-serine residue [Ser(All)], crystallizes in the monoclinic space group C2 with one molecule in the asymmetric unit. The compound is an analogue of the Ser140-Val142 segment of the water channel aquaporin-4 (AQP4). It forms a distorted type-II β-turn with a P(II)-3(10L)-P(II) backbone conformation (P(II) is polyproline II). The overall backbone conformation is markedly different from that of the CO(Pro139)-Val142 stretch of rat AQP4, but is quite similar to the corresponding segment of human AQP4, despite significant differences at the level of the individual residues. The side chain of the Ser(All) residue adopts a gauche conformation relative to the backbone CO-C(α) and C(α)-N bonds. The H atoms of the two CH(2) groups in the Ser(All) side chain are almost eclipsed. The crystal packing of the title compound is divided into one-molecule-thick layers, each layer having a hydrophilic core and distinct hydrophobic interfaces on either side.
标题化合物[系统名称为(6S,12S)-甲基6-(烯丙氧基甲基)-12-异丙基-2,2,9,9-四甲基-4,7,10-三氧代-3-氧杂-5,8,11-三氮杂十三烷-13-酸酯]，化学式为C(21)H(37)N(3)O(7)，含有研究较少的O-烯丙基-L-丝氨酸残基[Ser(All)]，结晶于单斜空间群C2中，不对称单元中有一个分子。该化合物是水通道蛋白4(AQP4)中Ser140-Val142片段的类似物。它形成了一种扭曲的II型β-转角，主链构象为P(II)-3(10L)-P(II)(P(II)为聚脯氨酸II)。整体主链构象与大鼠AQP4的CO(Pro139)-Val142片段明显不同，但与人类AQP4的相应片段非常相似，尽管在个别残基水平上存在显著差异。Ser(All)残基的侧链相对于主链的CO-C(α)和C(α)-N键呈gauche构象。Ser(All)侧链中两个CH(2)基团的H原子几乎呈重叠构象。标题化合物的晶体堆积被分为单分子厚的层，每层都有一个亲水核心，两侧有明显的疏水界面。
