Chao T L, Duker N J
Mutat Res. 1984 Jun-Jul;140(2-3):93-8. doi: 10.1016/0165-7992(84)90049-6.
PBS-2 phage DNA, which contains uracil in place of thymine, was used as substrate for both purified B. subtilis uracil-DNA glycosylase and a crude extract from M. luteus. Addition of [3H]5-azacytidine to the medium after phage infection resulted in substitution of 1.2% azacytosine for cytosine in DNA. Substrate DNA was also labeled with [14C]uracil. Neither enzyme preparation released tritiated bases from DNA. Analysis by S1 nuclease digestion show no increase in single-strandedness of the modified DNA. Enzymic release of uracil by the M. luteus extract was reduced by about 50% from the substituted substrate. By contrast, the rate of uracil excision by the purified enzyme was unaffected by the presence of DNA 5-azacytosine.
含有尿嘧啶而非胸腺嘧啶的PBS - 2噬菌体DNA被用作纯化的枯草芽孢杆菌尿嘧啶 - DNA糖基化酶和藤黄微球菌粗提物的底物。噬菌体感染后向培养基中添加[3H]5 - 氮杂胞苷导致DNA中1.2%的氮杂胞嘧啶取代了胞嘧啶。底物DNA也用[14C]尿嘧啶进行了标记。两种酶制剂都未从DNA中释放出氚化碱基。通过S1核酸酶消化分析表明，修饰后的DNA单链性没有增加。藤黄微球菌提取物对尿嘧啶的酶促释放从取代底物中减少了约50%。相比之下，纯化酶的尿嘧啶切除率不受DNA 5 - 氮杂胞嘧啶存在的影响。
