Synthesis and characterization of site-specific and stereoisomeric fjord dibenzo[a,l]pyrene diol epoxide-N6-adenine adducts:: Unusual thermal stabilization of modified DNA duplexes
Synthesis and characterization of site-specific and stereoisomeric fjord dibenzo[a,l]pyrene diol epoxide-N6-adenine adducts:: Unusual thermal stabilization of modified DNA duplexes
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DOI：
10.1021/tx010157k
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发表时间：
2002-02-01
影响因子：
4.1
通讯作者：
Geacintov, NE
中科院分区：
文献类型：
--
作者：
Ruan, Q;Kolbanovskiy, A;Geacintov, NE
峡湾多环芳烃化合物二苯并[a，l]芘（DB[a，I]P）在动物模型系统中的致瘤性显著高于海湾地区苯并[a]芘。DB[a，l]P及其峡湾区二醇环氧化物代谢物异常强的遗传毒性性质的分子起源引起了极大的兴趣，并被认为与形成的DNA加合物的结构特征有关。位点特异性修饰的寡核苷酸通过使5 ′-d（CTCTCACTTCC）（I）中的单个腺嘌呤残基与外消旋峡湾二醇环氧化物r11，t12-二氢二醇-t13，14-环氧化物-11，12，13，14-四氢二苯并-[a，l]芘（抗-DB [a，l]PDE）在水溶液中反应来制备。鉴定并纯化了四种不同的寡核苷酸I，其具有涉及DB[a，l]PDE的C14位置和N-6-dA之间的共价键的单个腺苷残基。monoclontide加合物的CD光谱类似于Li等人[Li等人（1999）Chem.Res.Toxicol. 12，758]，其通过CD和NMR方法的组合表征DB[a，l]-PDE-N-6-dA加合物。四种DB[a，l] PDE修饰的寡核苷酸中的每一种的立体化学性质是基于经验CD规则和其它方法的组合来指定的，并且不同于Li等人的那些。I与其互补链（IC）的未修饰的双链体的热熔点T-m，T-m = 43.8 +/-0.5 ℃，与含有立体异构的抗DB [a，l]PDE-N-6-dA损伤的相同双链体进行比较。霸王在DB[a，l]PDE残基的C14处具有R绝对构型的含有IC的损伤高6-8 ℃，而具有S构型的那些低6-10 ℃。在相同的序列背景下，来自峡湾PAH抗二醇环氧化物的苯并[g]菲的加成物观察到类似的效果，而双链体含有来自苯并[c]菲二醇环氧化物与1 R和18配置的病变表现出不变的T-m值。与此相反，在同一序列中，来自湾区苯并[a]芘二醇环氧化物（B[a]PDE）的损伤双链体的T-m值降低12度（10 R加合物）和19度（10 S加合物）。相对于具有湾区B[a]PDE-N6-dA加合物的双链体，具有峡湾PAH-N-6-dA损伤的双链体具有更高的热稳定性，这与通过人核苷酸切除修复酶进行切除的较低可切除性相关[Buterin et al. 2000）Cancer Res. 60，1849]。这些关系的影响进行了讨论，在峡湾和海湾地区PAH二醇环氧化物-N-6-DA病变的双链DNA的构象方面的现有知识。
The fjord polycyclic aromatic hydrocarbon compound dibenzo[a,l]pyrene (DB[a,I]P) is significantly more tumorigenic than the bay region benzo[a]pyrene in animal model systems. The molecular origins of the unusually strong genotoxic properties of DB[a,l]P and its fjord region diol epoxide metabolites are of great interest and are believed to be related to the structural characteristics of the DNA adducts formed. Site-specifically modified oligonucleotides were prepared by reacting the single adenine residue in 5'-d(CTCTCACTTCC) (I) with the racemic fjord diol epoxide r11,t12-dihydrodiol-t13,14-epoxide-11,12,13,14-tetrahydrodibenzo-[a,l]pyrene (anti-DB[a,l]PDE) in aqueous solutions. Four different oligonucleotides I with the single adenosine residues involving a covalent bond between the C14 position of DB[a,l]PDE and N-6-dA are identified and purified. The CD spectra of the mononucleotide adducts are similar to those of Li et al. [Li et al. (1999) Chem. Res. Toxicol. 12, 758] who characterized DB[a,l]-PDE-N-6-dA adducts by a combination of CD and NMR methods. The stereochemical properties of each of the four DB[a,l]PDE-modified oligonucleotides were assigned on the basis of a combination of empirical CD rules and other approaches and differ from those of Li et al. The thermal melting points, T-m, of the unmodified duplex of I with its complementary strand (IC), T-m = 43.8 +/- 0.5 degreesC, were compared with the same duplexes containing stereoisomeric antiDB[a,l]PDE-N-6-dA lesions. The T. of duplexes I.IC containing lesions with R absolute configurations at C14 of the DB[a,l]PDE residues are greater by 6-8 degreesC, while those with S configuration are lower by 6-10 degreesC. Similar effects are observed with adducts in the same sequence context derived from the fjord PAH anti-diol epoxides of benzo[g]chrysene, while duplexes containing lesions derived from benzo[c]phenanthrene diol epoxides with 1R and 18 configurations exhibit unchanged T-m values. In contrast, the T-m values of duplexes with lesions derived from the bay region benzo[a]pyrene diol epoxides (B[a]PDE) in the same sequence are lower by 12degrees (10R adducts) and by 19degrees (10S adducts). The greater thermal stabilities of duplexes with fjord PAH-N-6-dA lesions relative to those with bay region B[a]PDE-N6-dA adducts, are correlated with lower susceptibilities of excision by human nucleotide excision repair enzymes [Buterin et al. 2000) Cancer Res. 60, 1849]. The implications of these relationships are discussed in terms of present knowledge of the conformations of fjord and bay region PAH diol epoxide-N-6-dA lesions in double stranded DNA.