Chen X, Woodson S A, Burrows C J, Rokita S E
Department of Chemistry, State University of New York, Stony Brook 11794.
Biochemistry. 1993 Aug 3;32(30):7610-6. doi: 10.1021/bi00081a002.
A nickel complex has been shown to promote conformation-specific oxidation of guanosine in polynucleotide RNA. In all cases, reaction was strictly dependent on the solvent exposure and surface properties of guanine N7. Modification of native tRNA(Phe) (yeast) was detected at G18, G19, G20, and Gm34 and concurred with predictions based on its crystal structure. Additional guanine derivatives became exposed to oxidation only after the tRNA unfolded in the absence of Mg2+. Reaction of the Tetrahymena group I intron RNA (L-21 ScaI) also compared favorably to its three-dimensional model by appropriately identifying guanosine residues in hairpin loops, duplex termini, and the essential cofactor binding site. These results complemented prior data generated by hydroxyl radical, and in combination they served to distinguish the solvent accessibility of sugar backbone and base positions in guanosine residues. Most importantly, this nickel complex exhibited greater selectivity than either dimethyl sulfate or RNase T1 for characterizing tRNA(Phe) and intron RNA.
已证明一种镍配合物可促进多核苷酸RNA中鸟苷的构象特异性氧化。在所有情况下，反应都严格取决于鸟嘌呤N7的溶剂暴露情况和表面性质。在G18、G19、G20和Gm34处检测到天然酵母苯丙氨酸tRNA（tRNA(Phe)）发生了修饰，这与基于其晶体结构的预测结果一致。只有在没有Mg2+的情况下tRNA展开后，其他鸟嘌呤衍生物才会暴露于氧化反应中。通过适当识别发夹环、双链末端和必需辅因子结合位点中的鸟苷残基，嗜热四膜虫I组内含子RNA（L-21 ScaI）的反应也与其三维模型吻合良好。这些结果补充了之前由羟基自由基产生的数据，并且二者共同用于区分鸟苷残基中糖骨架和碱基位置的溶剂可及性。最重要的是，在表征tRNA(Phe)和内含子RNA方面，这种镍配合物比硫酸二甲酯或核糖核酸酶T1具有更高的选择性。
