MYELOPEROXIDASE ACTIVATION OF N ACETYLBENZIDINE

在接触联苯胺的工人中， N ′-（3 ′-单磷酸脱氧鸟苷-8-基）-N-乙酰基联苯胺（1A） 在膀胱脱落细胞和外周白色血细胞中检测到。 因为这两种细胞类型都表现出大量的过氧化物活性， 被认为是N-乙酰联苯胺活化的可能机制 （ABZ）。 因此，3 H-ABZ的髓过氧化物酶（MPO）代谢 (0.06用HPLC分析来评估。 物质代谢 观察到MPO引起的ABZ的2倍增加， 在反应混合物中加入100 mM NaCl。 牛磺酸（10 mM） 在存在NaCl的情况下代谢减少，但不存在NaCl。 叠氮化物（1 mM）、氰化物（10 mM）和抗坏血酸（1 mM）显著地 抑制新陈代谢。 使用谷胱甘肽（0.1 mM）， 观察到对β-谷氨酰转肽酶敏感， 用温和的酸或碱处理（0.1N HCl或0.1N NaOH 10分钟）。 在dGp、MPO或0.3mM NaOC存在下， 产生 一种加合物，其形成被以下物质的存在所阻止： 谷胱甘肽或维生素C。ESI/MS/MS分析证明了该加合物 是1A。 因此，ABZ是MPO的还原性共底物，并且ABZ是MPO的还原性共底物。 OCl-的还原剂。 MPO可能参与ABZ的激活 由外周白色血细胞形成1A。

In workers exposed to benzidine, N'-(3'-monophospho-deoxyguanosin-8 -yl)-N-acetylbenzidine (1A) was detected in exfoliated bladder cells and peripheral white blood cells. Because both cell types exhibit substantial peroxidatic activity, this was considered a likely mechanism for activation of N-acetylbenzidine (ABZ). For this reason, myeloperoxidase (MPO) metabolism of 3H-ABZ (0.06 mM) was assessed with analysis by HPLC. Substantial metabolism of ABZ by MPO was observed with a 2-fold increase elicited by inclusion of 100 mM NaCl in the reaction mixture. Taurine (10 mM) reduced metabolism in the presence, but not the absence of NaCl. Azide (1 mM), cyanide (10 mM), and ascorbic acid (1 mM) dramatically inhibited metabolism. With glutathione (0.1 mM), a new metabolite was observed which was sensitive to (-glutamyl transpeptidase and hydrolyzed to ABZ with mild acid or base treatment (0.1 N HCl or 0.1 N NaOH for 10 min). In the presence of dGp, MPO or 0.3 mM NaOC l produced an adduct whose formation was prevented by the presence of either glutathione or vitamin C. ESI/MS/MS analysis demonstrated this adduct to be 1A. Thus, ABZ is a reducing co-substrate for MPO and a reductant for OCl-. MPO may be responsible for the activation of ABZ by peripheral white blood cells to form 1A.