Differential excision from DNA of the C-8 and N2 guanosine adducts of N-acetyl-2-aminofluorene by single strand-specific endonucleases.
Differential excision from DNA of the C-8 and N2 guanosine adducts of N-acetyl-2-aminofluorene by single strand-specific endonucleases.
复制标题
通过单链特异性核酸内切酶从 N-乙酰基-2-氨基芴的 C-8 和 N2 鸟苷加合物的 DNA 中进行差异性切除。
作者：
H. Yamasaki;P. Pulkrabek;D. Grunberger;I. Weinstein
纯化的鸭网织细胞DNA与[9-14C]- n -乙酰氧基- n -乙酰基-2-氨基芴在体外反应。用Sephadex LH-20色谱柱对[14C]-N-乙酰基-2-氨基芴修饰的DNA进行水解，结果表明结合的[14C]-N-乙酰基-2-氨基芴中85%为N-（脱氧鸟苷-8-基）-N-乙酰基-2-氨基芴，15%为3-（脱氧鸟苷- n2 -基）-N-乙酰基-2-氨基芴。当修饰后的DNA与单链特异性核酸酶S1孵育，并分析未消化的DNA部分时，DNA中的氨基糖C-8加合物优先丢失。此外，将n -乙酰基-2-氨基芴修饰的DNA暴露于来自粗神经孢子虫的单链特异性核酸酶所释放的核苷分析显示，在上清部分中只有鸟苷C-8加合物。这些结果表明，DNA中的N-（脱氧鸟苷-8-基）-N-乙酰基-2-氨基芴加合物引起双链螺旋和局部变性区域的主要构象变化，而3-（脱氧鸟苷- n2 -基）-N-乙酰基-2-氨基芴加合物不会引起天然DNA结构的主要扭曲。
Purified duck reticulocyte DNA was reacted in vitro with [9-14C]-N-acetoxy-N-acetyl-2-aminofluorene. Hydrolysis of the [14C]-N-acetyl-2-aminofluorene-modified DNA followed by Sephadex LH-20 column chromatography showed that 85% of the DNA-bound [14C]-N-acetyl-2-aminofluorene was N-(deoxyguanosin-8-yl)-N-acetyl-2-aminofluorene and 15% was 3-(deoxyguanosin-N2-yl)-N-acetyl-2-aminofluorene. When this modified DNA was incubated with the single strand-specific nuclease, S1, and the undigested fraction of the DNA was analyzed, there was preferential loss of the quanosine C-8 adduct from the DNA. Moreover, analysis of the nucleosides released by exposure of N-acetyl-2-aminofluorene-modified DNA to a single strand-specific nuclease from Neurospora crassa showed only the guanosine C-8 adduct in the supernatant fraction. These results suggest that, whereas the N-(deoxyguanosin-8-yl)-N-acetyl-2-aminofluorene adduct in DNA causes major conformational changes in the double-stranded helix and localized regions of denaturation, the 3-(deoxyguanosin-N2-yl)-N-acetyl-2-aminofluorene adduct does not cause major distortions of the native DNA structure.