Use of chemically modified nucleotides to determine a 62-nucleotide RNA crystal structure: A survey of phosphorothioates, Br, Pt and Hg
Use of chemically modified nucleotides to determine a 62-nucleotide RNA crystal structure: A survey of phosphorothioates, Br, Pt and Hg
复制标题
DOI：
10.1080/07391102.1997.10508183
复制
发表时间：
1997-10-01
影响因子：
4.4
通讯作者：
Steitz, TA
中科院分区：
文献类型：
--
作者：
Correll, CC;Freeborn, B;Steitz, TA
RNA结晶学家面临的两个重要挑战是生产晶体和寻找同构的重原子衍生物。非同构可以通过使用多波长反常色散(MAD)方法确定位相来解决。通过将在不同重原子衍生物上进行的MAD实验的相组合起来，这些相可以得到极大的改善。重原子衍生物可以通过将溴或汞共价连接到嘧啶的C5上或将[铂(NH3)3](2+)连接到鸟嘌呤的N7上来化学修饰RNA。虽然硫代磷可以提供汞结合部位，但无序会降低它们在相测定中的价值。这些化学修饰的位置是关键的，因为这些衍生的RNA的结晶对重原子诱导的构象变化和晶体堆积很敏感。
Two important challenges confronting RNA crystallographers are producing crystals and finding isomorphous heavy-atom derivatives. Non-isomorphism can be addressed by determining the phases using the multiwavelength anomalous dispersion (MAD) method. These phases can be greatly improved by combining phases from MAD experiments done on different heavy-atom derivatives. Heavy-atom derivatives can be created by chemically modifying the RNA through covalent attachment of bromine or mercury to C5 of pyrimidines or [Pt(NH3)3](2+) to N7 of guanine. While phosphorothioates can provide mercury binding sites, disorder can reduce their value for phase determination. The location of these chemical modifications is critical since crystallization of these derivatized RNAs is sensitive to heavy atom induced conformational alterations and crystal packing.