Mitomycin C (MMC) binds to deoxyribonucleic acid (DNA) after its reductive activation by catalytic hydrogenation with Pd on charcoal. Three modified nucleotides, named MG-1, MG-2 and MA, were isolated and purified by high performance liquid chromatography (HPLC) from the modified DNA after enzymatic hydrolysis to 5'-nucleotides with nuclease P1. Analysis of the proton nuclear magnetic resonance (1H-NMR) and ultraviolet (UV) spectra, and studies of the acid and enzymatic hydrolysates of these modified nucleotides suggested that MG-1 and MG-2 are deoxyguanylic acid-MMC adducts bound at position 1 of mitosene and a heteroatom of the guanine moiety. Analogous binding to an adenine moiety is proposed for the adduct, MA. Chemical transformations (methylation, diazotization and thioketonization) were used to unambiguously determine the binding sites of the purine bases. The binding sites were identified as the N2 atom of guanine for MG-1, the O6 atom of guanine for MG-2, and the N6 atom of adenine for MA. Thus, these three modified nucleotides were concluded to be 1, 2-trans-2, 7-diamino-1-(N2-deoxyguanylyl) mitosene (MG-1), 2, 7-diamino-1-(O6-deoxyguanylyl) mitosene (MG-2), and 2, 7-diamino-1-(N6-deoxyadenylyl) mitosene (MA). These same modified nucleotides were identified in DNA extracted from the livers of rats treated with MMC.
Mitomycin C (MMC) 在经过 Pd 催化氢化还原激活后,与
脱氧核糖核酸 (DNA) 结合。通过与
核酸酶 P1 的酶促
水解,将修改后的 DNA 提取出来,并使用高效
液相色谱法 (HPLC) 分离和纯化了三种修饰核苷酸,分别命名为 MG-1、MG-2 和 MA。对质子核磁共振 (1H-NMR) 和紫外 (UV) 光谱的分析,以及对这些修饰核苷酸的酸性和酶促
水解物的研究表明,MG-1 和 MG-2 是与去氧
鸟苷酸-MMC 结合的产物,结合位点在 mitosene 的第 1 位和
鸟苷体的一个杂原子上。对于产物 MA,提出了与
腺苷体的类似结合。
化学转化(甲基化、重氮化和
硫酮化)被用来明确确定
嘌呤碱基的结合位点。结合位点被确定为 MG-1 的
鸟苷 N2 原子、MG-2 的
鸟苷 O6 原子以及 MA 的
腺苷 N6 原子。因此,这三种修饰核苷酸被总结为 1, 2-trans-2, 7-二
氨基-1-(N2-去氧
鸟苷酸) mitosene (MG-1)、2, 7-二
氨基-1-(O6-去氧
鸟苷酸) mitosene (MG-2) 和 2, 7-二
氨基-1-(N6-去氧
腺苷酸) mitosene (MA)。这些相同的修饰核苷酸在用 MMC 处理的大鼠肝脏提取的 DNA 中被确认存在。