Hayakawa H, Kumura K, Sekiguchi M
J Biochem. 1978 Nov;84(5):1155-64. doi: 10.1093/oxfordjournals.jbchem.a132231.
Uracil-DNA glycosylase, which acts specifically on uracil-containing DNA, was purified 250-fold from an extract of Escherichia coli 1100. The enzyme releases free uracil from DNA, producing alkali-labile apyrimidinic sites in the DNA. The enzyme is active on both native and heat-denatured DNA of phage PBS1, which contains uracil in place of thymine. piX174 DNA which had been treated with bisulfite and then at alkaline pH was susceptible to the action of uracil-DNA glycosylase. Since DNA treated with bisulfite alone was less susceptible to the enzyme, it is likely that the enzyme recognizes deaminated cytosine, namely uracil, but not bisulfite adducts of uracil and cytosine in the treated DNA. DNA treated with nitrite or hydroxylamine was not attacked by the enzyme. Enzyme activity acting on bisulfite-treated DNA was absent from an extract of E. coli mutant BD10 (ung). The mutant exhibited higher sensitivity to bisulfite than did the wild-type strain and was unable to reactivate phage T1 pre-exposed to bisulfite and weak alkali.
尿嘧啶-DNA糖基化酶能特异性作用于含尿嘧啶的DNA，从大肠杆菌1100提取物中纯化了250倍。该酶从DNA中释放游离尿嘧啶，在DNA中产生碱不稳定的无嘧啶位点。该酶对噬菌体PBS1的天然和热变性DNA均有活性，PBS1的DNA中尿嘧啶取代了胸腺嘧啶。经亚硫酸氢盐处理后再在碱性pH下处理的噬菌体φX174 DNA对尿嘧啶-DNA糖基化酶的作用敏感。由于单独用亚硫酸氢盐处理的DNA对该酶不太敏感，所以该酶可能识别脱氨基的胞嘧啶，即尿嘧啶，但不识别处理后DNA中尿嘧啶和胞嘧啶的亚硫酸氢盐加合物。用亚硝酸盐或羟胺处理的DNA不受该酶攻击。大肠杆菌突变体BD10（ung）的提取物中不存在作用于亚硫酸氢盐处理DNA的酶活性。该突变体比亚型菌株对亚硫酸氢盐表现出更高的敏感性，并且无法重新激活预先暴露于亚硫酸氢盐和弱碱的噬菌体T1。
