PROSTAGLANDIN H SYNTHASE PEROXIDATIC FORMATION OF N HYDROXY N ACETYL BENZIDINE

前列腺素H合成酶(PHS)激活芳香胺 膀胱癌致癌物N-乙酰联苯胺(ABZ)的形成 N‘-(3’-单磷-脱氧鸟苷-8-基)-N-乙酰基联苯胺和 4‘-硝基-4-乙酰氨基联苯(4-硝基-ABZ)。前一个加法是 被认为会导致突变，最终可能导致肿瘤 队形。本报告评估了~3H-ABZ(0.06 mM)的作用机制 用绵羊精囊微粒体进行PHS的过氧化激活 并用高效液相色谱仪进行分析。抗坏血酸抑制4-硝基-ABZ的形成 并增加了由ESI/MS/MS鉴定的新的峰 N‘-羟基-N-乙酰基联苯胺(N’Ha)。观察了N‘Ha是否 以花生四烯酸(0.2 mM)或过氧化氢(0.5 mM)为底物。 当存在未标记的0.05 mM N‘Ha时，~3H-4-硝基-ABZ的含量降低 ~3H-N‘Ha也相应增加。小灵通 将N‘Ha定量转化为4-硝基-ABZ。氰化物(10毫米)，a 过氧化物酶抑制剂，阻止新陈代谢，但细胞色素P-450 缓蚀剂SKF-525A、呋喃呋喃或-萘黄酮(0.1 mM)起作用 不。苯丁酮的PHS代谢，而不是ABZ 摄氧量。因此，N‘Ha是过氧剂中的中间体 小灵通激活ABZ，并可能参与形成 DNA加合物。这是第一个证明形成一个 N-羟基芳胺通过过氧化途径。

Prostaglandin H synthase (PHS) activates the aromatic amine bladder carcinogen N-acetylbenzidine (ABZ) to form N'-(3'-monophospho-deoxyguanosin-8- yl)-N-acetylbenzidine and 4'-nitro-4-acetylaminobiphenyl (4-nitro-ABZ). The former adduct is thought to cause mutations that may eventually lead to tumor formation. This report assesses the mechanism of 3H-ABZ (0.06 mM) peroxidatic activation by PHS, using ram seminal vesicle microsomes with analysis by HPLC. Ascorbic acid inhibits 4-nitro-ABZ formation and increases a new peak identified by ESI/MS/MS as N'-hydroxy-N-acetylbenzidine (N'HA). N'HA was observed whether arachidonic acid (0.2 mM) or H2O2 (0.5 mM) were used as the substrate. When unlabeled 0.05 mM N'HA was present, a decrease in 3H-4-nitro-ABZ and corresponding increase in 3H-N'HA was observed. PHS quantitatively converted N'HA to 4-nitro-ABZ. Cyanide (10 mM), a peroxidase inhibitor, prevented metabolism, but cytochrome P-450 inhibitors SKF-525A, furafyl line, or ( -naphthoflavone (0.1 mM) did not. PHS metabolism of phenylbutazone, but not ABZ, demonstrated oxygen uptake. Thus, N'HA is an intermediate in the peroxidatic activation of ABZ by PHS and may participate in the formation of the DNA adduct. This is the first report to demonstrate formation of an N-OH arylamine by a peroxidatic pathway.