Denaturation and renaturation studies of benzo[a]pyrene metabolite modified DNAs.
Denaturation and renaturation studies of benzo[a]pyrene metabolite modified DNAs.
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苯并[a]芘代谢物修饰 DNA 的变性和复性研究。
DOI：
10.1021/bi00388a021
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发表时间：
1987
期刊：
影响因子：
2.9
通讯作者：
Chen,FM
中科院分区：
文献类型：
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作者：
Chen,FM
田纳西州州立大学化学系，纳什维尔，田纳西州37203接收日期：1986年12月11日;修订版：1987年3月11日摘要：来自吸光度、荧光和圆二色性（CD）测量的证据强烈表明，在（+）-i/mr-7的热变性之前和之后，结合位点处的加合物构象明显不同，8-二羟基-α-氮杂-9，10-环氧-7，8，9，10-四氢苯并[a]芘[（+）-α-氮杂-BPDE]修饰的DNA。这一结论是通过以下观察得到的：（1）在熔融和冷却时，（+）-aniz-BPDE修饰的DNA出现减色效应，并伴随着芘基吸收光谱的红移：（2）芘基CD光谱在热变性-复性时反号;（3）在353 nm激发下的荧光发射光谱（10 nm至水解和未结合的'-BPDE的红色）对于热变性和冷却的加合物表现出增强的强度和光谱红移;和（4）与熔融前不存在肩相反，当监测384-387-nm发射时，熔融后加合物在激发光谱中表现出突出的355-nm最大值（堆积相互作用的证据）。合成多核苷酸的研究进一步揭示了（+）-aniz '-BPDE修饰的poly（dG）-poly（dC）在结合位点表现出最大的不可逆复性，可能是芘基自堆积的结果。这一点，加上先前的发现，即该聚合物遭受最广泛的（+）-aniz '-BPDE修饰，似乎表明（dG）n-（dC）n区域可能是天然DNA中观察到的这种效应的原因。
Department of Chemistry, Tennessee State University, Nashville, Tennessee 37203 Received December 11, 1986; Revised Manuscript Received March 11, 1987 abstract: Evidence from absorbance, fluorescence, and circular dichroism (CD) measurements strongly suggests that adduct conformations at the binding sites are grossly different before and after thermal denaturation of (+)-í/mr-7, 8-dihydroxy-aŦíz-9, 10-epoxy-7, 8, 9, 10-tetrahydrobenzo [a] pyrene [(+)-aŦiz'-BPDE] modified DNAs. This conclusion is reached through the following observations:(1) upon melting and cooling, the (+)-aniz-BPDE-modified DNA exhibitspronounced hypochromic effects with concomitantspectral red shifts for the pyrenyl absorbance;(2) the pyrenyl CD spectrum reverses sign upon thermal denaturationrenaturation;(3) thefluorescence emission spectra resultingfrom excitationsat 353 nm (10 nm to the red of hydrolyzed and unbound'-BPDE) exhibit enhanced intensities and spectral red shifts for the thermally denatured and cooled adducts; and (4) in contrast to the absence of a shoulder prior to melting, the postmelt adducts exhibit a prominent 355-nm maximum (evidence of stacking interactions) in the excitation spectrum when 384-387-nm emission is monitored. Studies with synthetic polynucleotides further reveal that (+)-aniz'-BPDE-modified poly (dG)-poly (dC) exhibits thegreatest nonreversible renaturation at the binding sites, possibly as a consequence of pyrenyl self-stacking. This, coupled with the previous findingsthat this polymer suffers the most extensive (+)-aniz'-BPDE modification, appears to suggest that (dG)„-(dC)„regions may be responsible for such observed effects in native DNA.