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首页> 外文期刊>Biochemistry >SEQUENCE-SELECTIVE DNA RECOGNITION AND PHOTOCLEAVAGE - A COMPARISON OF ENANTIOMERS OF RH(EN)(2)PHI(3+)
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SEQUENCE-SELECTIVE DNA RECOGNITION AND PHOTOCLEAVAGE - A COMPARISON OF ENANTIOMERS OF RH(EN)(2)PHI(3+)

机译：序列选择性DNA的识别和光切割-RH（EN）（2）PHI（3+）对映体的比较

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摘要

The recognition and photoinduced cleavage of DNA by the enantiomers of bis(ethylenediamine)(9,10-phenanthrenequinone diimine)Rh(III) [Rh(en)(2)phi(3+)] have been characterized and the basis for enantioselective differences delineated. Rh(en)(2)phi(3+) isomers bind strongly to DNA via intercalation and, upon photoactivation with near-UV light, produce direct strand cleavage. On the basis of product analysis, the photoinduced DNA cleavage appears to proceed by a mechanism consistent with that observed for the parent Rh(phen)(2)phi(3+), involving direct abstraction of the 3'-hydrogen atom of the deoxyribose by the activated, intercalated phi. Quantitative photocleavage, titrations indicate tight binding by both enantiomers to the DNA duplex. For Delta-Rh(en)(2)phi(3+), DNA site affinities range from 0.3 x 10(6) to 8.0 x 10(6) M(-1), and a distinct preference for GC sites is evident. Lambda-Rh(en)(2)phi(3+) is found to be sequence neutral with an average site affinity of 2 x 10(6) M(-1). The basis for sequence selectivity of the enantiomers has been examined through comparison of photocleavage patterns to those of several phi complexes of rhodium(III) containing or lacking axial amines; those complexes containing the axial amines are found to target GC sites. DNA photocleavage studies on oligonucleotides containing the modified bases O-6-methylguanine, 7-deazaguanine, and deoxyuracil have been utilized to determine points of interaction on the DNA helix. These results establish binding by both complexes in the major groove of DNA. Differences in site recognition between enantiomers are attributed to the different hydrogen bonding and van der Waals contacts available in the major groove for the ancillary ethylenediamine ligands which differ in disposition in the two isomers.
机译：双（乙二胺）（9,10-菲醌二亚胺）Rh（III）[Rh（en）（2）phi（3+）]的对映异构体对DNA的识别和光诱导裂解已被表征，并且是对映选择性差异的基础划定的。 Rh（en）（2）phi（3+）异构体通过嵌入与DNA牢固结合，并在用近紫外光进行光激活后产生直接的链断裂。根据产物分析，光诱导的DNA裂解似乎是通过与对母体Rh（phen）（2）phi（3+）观察到的机制一致的方式进行的，涉及直接提取脱氧核糖的3'-氢原子通过激活的，插入的phi。定量光裂解，滴定表明两种对映异构体与DNA双链体紧密结合。对于Delta-Rh（en）（2）phi（3 +），DNA位点亲和力范围从0.3 x 10（6）到8.0 x 10（6）M（-1），并且对于GC位点有明显的偏好。 Lambda-Rh（en）（2）phi（3+）被发现是序列中性的，平均位点亲和力为2 x 10（6）M（-1）。对映体的序列选择性的基础已经通过将光裂解模式与含有或不具有轴向胺的铑（III）的几种phi络合物的光裂解模式进行了比较来检验;那些含有轴向胺的络合物被发现靶向GC位点。对含有修饰碱基O-6-甲基鸟嘌呤，7-脱氮鸟嘌呤和脱氧尿嘧啶的寡核苷酸的DNA光裂解研究已用于确定DNA螺旋上的相互作用点。这些结果在DNA的主要沟中建立了两种复合物的结合。对映异构体之间在位点识别上的差异归因于辅助乙二胺配体在主要凹槽中可利用的氢键和范德华接触不同，这两种异构体的位置不同。

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