32P-postlabeling analysis of IQ, MeIQx and PhIP adducts formed in vitro in DNA and polynucleotides and found in vivo in hepatic DNA from IQ-, MeIQx- and PhIP-treated monkeys.
32P-postlabeling analysis of IQ, MeIQx and PhIP adducts formed in vitro in DNA and polynucleotides and found in vivo in hepatic DNA from IQ-, MeIQx- and PhIP-treated monkeys.
复制标题
对体外 DNA 和多核苷酸中形成的 IQ、MeIQx 和 PhIP 加合物进行 32P 标记后分析，并在体内 IQ、MeIQx 和 PhIP 处理的猴子的肝 DNA 中发现。
作者：
E. Snyderwine;C. Davis;K. Nouso;P. Roller;H. Schut
用~（32）P后标记法研究了2-氨基-3-甲基咪唑[4，5-f]喹啉（IQ）、2-氨基-3，8-二甲基咪唑[4，5-f]喹喔啉（MeIQx）和2-氨基-1-甲基-6-苯基咪唑[4，5-B]吡啶（PhIP）的N-羟基和N-乙酰氧基衍生物与DNA、多核苷酸和单核苷酸的体外加合物。将加合物谱与喂食IQ、MeIQx或PhIP的食蟹猴肝脏中的体内加合物谱进行比较。IQ、MeIQx和PhIP的N-乙酰氧基衍生物（在醋酸酐存在下由相应的N-羟胺原位生成）各自形成DNA中的三种主要加合物。IQ、MeIQx和PhIP的加合物1在色谱上分别与N-（脱氧鸟苷-8-基）-IQ、N-（脱氧鸟苷-8-基）-MeIQx和N-（脱氧鸟苷-8-基）-PhIP的32 P标记的双（磷酸）衍生物相同，并且该加合物占体外DNA中发现的总加合物水平的约65%。在聚（dG-dC）中还发现了C8-鸟嘌呤加合物和两种次要加合物。聚（dG-dC），这表明IQ的两个次要加合物MeIQx和PhIP也在鸟嘌呤碱基上形成。IQ的N-乙酰氧基衍生物、MeIQx和在较小程度上PhIP也与含腺嘌呤的多核苷酸形成加合物，包括poly（dA）、poly（dA）.poly（dT）和poly（dA-dT）.poly（dA-dT），但这些腺嘌呤加合物在色谱上不同于DNA中发现的那些。在体外DNA和含鸟嘌呤的多核苷酸中发现的N-乙酰氧基-IQ、-MeIQx和-PhIP的三种鸟嘌呤加合物也分别在喂食IQ、MeIQx或PhIP的猴子的肝脏中发现，表明猴子体内发生了通过N-羟基化和酯化的代谢活化。对于每种化合物，C8-鸟嘌呤加合物是体内发现的主要加合物。结果表明IQ，MeIQx和PhIP之间的相似性在体外和体内形成的DNA加合物，并证实了使用的32 P-postlabeling方法比较加合物研究。
The 32P-postlabeling method was used to examine the adducts in DNA, polynucleotides, and mononucleotides reacted in vitro with the N-hydroxy and N-acetoxy derivatives of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3, 8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) or 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Adduct profiles were compared to those found in vivo in liver of cynomolgus monkeys fed IQ, MeIQx or PhIP. The N-acetoxy derivatives of IQ, MeIQx and PhIP (generated in situ from the corresponding N-hydroxylamine in the presence of acetic anhydride) each formed three principal adducts in DNA. Adduct 1 of IQ, MeIQx and PhIP was chromatographically identical to the 32P-labeled bis(phosphate) derivative of N-(deoxyguanosin-8-yl)-IQ, N-(deoxyguanosin-8-yl)-MeIQx, and N-(deoxyguanosin-8-yl)-PhIP respectively, and this adduct comprised approximately 65% of total adduct levels found in DNA in vitro. The C8-guanine adduct and the two minor adducts were also found in poly(dG-dC). poly(dG-dC), suggesting that the two minor adducts of IQ, MeIQx and PhIP are also formed on the guanine base. The N-acetoxy derivatives of IQ, MeIQx, and to a much lesser extent PhIP, also formed adducts with adenine-containing polynucleotides including poly(dA), poly(dA).poly(dT) and poly(dA-dT).poly(dA-dT), but these adenine adducts were chromatographically different from those found in DNA. The three guanine adducts of N-acetoxy-IQ, -MeIQx and -PhIP found in vitro in DNA and in guanine-containing polynucleotides were also found in the liver of monkeys fed IQ, MeIQx or PhIP respectively, indicating that metabolic activation via N-hydroxylation and esterification occurred in vivo in monkeys. With each compound, the C8-guanine adduct was the predominant adduct found in vivo. The results indicate similarities among IQ, MeIQx and PhIP in the DNA adducts formed in vitro and in vivo and substantiate the use of the 32P-postlabeling method for comparative adduct studies.