- Synthesis and crystal structure of 2'-Se-modified guanosine containing DNA
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(Chemical Equation Presented) Selenium modification of nucleic acids is of great importance in X-ray crystal structure determination and functional study of nucleic acids. Herein, we describe a convenient synthesis of a new building block, the 2′-SeMe-modified guanosine (GSe) phosphoramidite, and report the first incorporation of the 2′-Se-G moiety into DNA. The X-ray crystal structure of the 2′-Se-modified octamer DNA (5′-GTGSeTACAC-3′) was determined at a resolution of 1.20 A.We also found that the 2′-Se modification points to the minor groove and that the modified and native structures are virtually identical. Furthermore, we observed that the 2′-Se-G modification can significantly facilitate the crystal growth with respect to the corresponding native DNA.
- Salon, Jozef,Sheng, Jia,Gan, Jianhua,Huang, Zhen
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scheme or table
p. 637 - 641
(2010/04/29)
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- Synthesis, oxidation behavior, crystallization and structure of 2′-methylseleno guanosine containing RNAs
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We have recently introduced a basic concept for the combined chemical and enzymatic preparation of site-specifically modified 2′-methylseleno RNAs which represent useful derivatives for phasing of X-ray crystallographic data during their three-dimensional structure determination. Here, we introduce the first synthesis of an appropriate guanosine phosphoramidite, which complements the thus far established set of 2′-methylseleno-modified uridine, cytidine, and adenosine building blocks for solid-phase synthesis. The novel building block was readily incorporated into RNA. Importantly, it was the 2′-methylselenoguanosine-labeled RNA that allowed us to reveal the reversible oxidation/reduction behavior of the Se moiety and thus it represents a valuable contribution to the understanding of the action of threo-1,4-dimercapto-2,3-butanediol (DTT) required during solid-phase synthesis, deprotection, and crystallization of selenium-containing RNA. In addition, we investigated 2′-methylseleno RNA with respect to crystallization properties. Our studies revealed that the Se modification significantly increases the range of conditions leading to crystal growth. Moreover, we determined the crystal structures of model RNA helices and showed that the Se modification can affect crystal packing interactions, thus potentially expanding the possibilities for obtaining the best crystal form.
- Moroder, Holger,Kreutz, Christoph,Lang, Kathrin,Serganov, Alexander,Micura, Ronald
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p. 9909 - 9918
(2007/10/03)
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