Mansy S, Peticolas W L
Biochemistry. 1976 Jun 15;15(12):2650-5. doi: 10.1021/bi00657a026.
A laser Raman study of the alkylation of calf thymus DNA, poly(dG)-poly(dC) and poly(dA)-(dT) has been made using two water soluble alkylating agents: an antitumor drug, the difunctional methyl nitrogen mustard (HN2), which froms interstrand cross-links, and the dimethyl nitrogen half mustard (HN1). When an excess of the alkylating agent was used, the observed Raman frequencies due to the guanine ring modes in DNA and poly(dG)-poly(dC) changed virtually quantitatively to those of 7-methylguanosine (7-Me-Guo) showing that essentially all of the guanine bases were alkylated in the N-7 position. Furthermore, this alkylated DNA formed a stable double helical complex at neutral pH in which the alkylated guanine residues are in the keto form. No changes in the Raman bands of any of the other bases were observed in alkylated DNA. The DNA double helix, completely alkylated in at the N-7 position of guanine, melts about 35 degrees C below that of the native DNA. Upon melting, the alkylated guanine changes from the keto to the zwitterionic form.
使用两种水溶性烷基化剂，对小牛胸腺DNA、聚（dG）-聚（dC）和聚（dA）-（dT）的烷基化进行了激光拉曼研究：一种抗肿瘤药物，双功能甲基氮芥（HN2），它能形成链间交联，以及二甲基氮半芥（HN1）。当使用过量的烷基化剂时，DNA和聚（dG）-聚（dC）中鸟嘌呤环模式所观察到的拉曼频率实际上定量地转变为7-甲基鸟苷（7-Me-Guo）的频率，这表明基本上所有的鸟嘌呤碱基都在N-7位被烷基化。此外，这种烷基化的DNA在中性pH下形成了稳定的双螺旋复合物，其中烷基化的鸟嘌呤残基处于酮式。在烷基化的DNA中未观察到任何其他碱基的拉曼带发生变化。在鸟嘌呤的N-7位完全烷基化的DNA双螺旋，其熔点比天然DNA低约35摄氏度。在熔化时，烷基化的鸟嘌呤从酮式转变为两性离子形式。
