CRYSTAL STRUCTURE OF 5-METHYLURIDINE
CRYSTAL STRUCTURE OF 5-METHYLURIDINE
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DOI：
10.1107/s0567740869005267
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发表时间：
1969-01-01
期刊：
影响因子：
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通讯作者：
SUBRAMANIAN, E
中科院分区：
文献类型：
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作者：
HUNT, DJ;SUBRAMANIAN, E
5-甲基尿苷是以乙醇为半水合物，以正交针状结晶而成，空间群为P21212，晶胞参数为a=14.026，b=17.302，c=4.861，每个晶胞4个分子。通过三维X射线衍射分析确定了其晶体结构。强度数据收集在照相胶片上，并进行目测。利用傅立叶技巧和填充考虑，从Patterson函数求出了该结构。用全矩阵最小二乘法进行精炼，得到1294次反射的最终R值为0.075，并估计了非氢原子键长的标准偏差在0-006和0.007/~之间。描述糖渣和嘧啶碱基相对取向的扭角为-29-4。糖渣的C(Y)原子通过其他四个环原子从最小二乘平面移位约0.60/~，并与C(5‘)位于平面的同一侧。该平面还与最小二乘平面通过嘧啶碱基的六个环原子成71.9度角。在嘧啶环内或与其键合的12个原子中，只有C(I‘)通过6个环原子与最小二乘平面有显著偏离0-083/~。
5-Methyluridine was crystallized from aqueous ethanol as the hemihydrate in the form of ortho-rhombic needles, space group P21212 with a= 14.026, b= 17.302, c= 4.861 A and four molecules per cell. The crystal structure has been determined by a three-dimensional, X-ray diffraction analysis. Intensity data were collected on photographic film and estimated visually. The structure was solved from the Patterson function with the help of Fourier techniques and packing considerations. Refine-ment by a full-matrix, least-squares method has led to a final R value of 0.075 for 1294 reflections and to estimated standard deviations in bond lengths for the non-hydrogen atoms between 0-006 and 0.007/~. The torsion angle describing the relative orientations of the sugar residue and the pyrimidine base is-29-4. Atom C (Y) of the sugar residue is displaced by about 0.60/~ from the least-squares plane through the other four ring atoms and lies on the same side of the plane as C (5'). This plane also makes an angle of 71.9 with the least-squares plane through the six ring atoms of the pyrimidine base. Of the twelve atoms within, or bonded to, the pyrimidine ring, only C (I') deviates significantly, by 0-083/~, from the least-squares plane through the six ring atoms.