Perturbations of enzymic uracil excision due to purine damage in DNA.
Perturbations of enzymic uracil excision due to purine damage in DNA.
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DNA 中嘌呤损伤导致酶促尿嘧啶切除的干扰。
DOI：
10.1073/pnas.79.16.4878
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发表时间：
1982
影响因子：
11.1
通讯作者：
Fishbein,DE
中科院分区：
文献类型：
--
作者：
Duker,NJ;Jensen,DE;Hart,DM;Fishbein,DE
噬菌体PBS-2 DNA，其中含有尿嘧啶代替胸腺嘧啶，被选择性地破坏，然后用作纯化的枯草芽孢杆菌尿嘧啶-DNA糖基化酶的底物。这种酶以有限的进行性方式从DNA中释放尿嘧啶。在异丙醇和自由基光引发剂存在下，通过紫外光（大于305 nm）照射将共价结合的8-（2-羟基-2-丙基）嘌呤引入DNA中。用硫酸二甲酯甲基化得到7-甲基鸟嘌呤。通过温和加热甲基化DNA产生脱嘌呤位点。尿嘧啶从DNA中的酶促释放速率在这三种底物中各不相同。Vmax显着降低的DNA含有8-（2-羟基-2-丙基）嘌呤和脱嘌呤位点，但不受大量的7-甲基鸟嘌呤的存在下。这表明某些类型的受损DNA部分可能会降低尿嘧啶切除的能力。因此，干扰这种潜在致突变碱基的酶切可能构成几种不相关DNA损伤剂反应产物的共同作用机制。
Phage PBS-2 DNA, which contains uracil in place of thymine, was selectively damaged and then used as substrate for purified Bacillus subtilis uracil-DNA glycosylase. This enzyme releases uracil from DNA in a limited processive manner. Irradiation by ultraviolet light (greater than 305 nm) in the presence of isopropanol and a free radical photoinitiator introduced covalently bound 8-(2-hydroxy-2-propyl)purines into DNA. Methylation by dimethylsulfate yielded 7-methylguanine. Apurinic sites were produced by gentle heating of methylated DNA. Rates of enzymic release of uracil from DNA varied among these three substrates. The Vmax was markedly decreased for DNA containing 8-(2-hydroxy-2-propyl)purines and apurinic sites but was unaffected by the presence of larger quantities of 7-methylguanine. This suggests that certain types of damaged DNA moieties may decrease the capacity for uracil excision. Therefore, interference with enzymic excision of this potentially mutagenic base may constitute a common mechanism of action of the reaction products of several unrelated DNA damaging agents.