Isoniazid as a substrate and inhibitor of myeloperoxidase: Identification of amine adducts and the influence of superoxide dismutase on their formation
作者:Louisa V. Forbes、Paul G. Furtmüller、Irada Khalilova、Rufus Turner、Christian Obinger、Anthony J. Kettle
DOI:10.1016/j.bcp.2012.07.020
日期:2012.10
MPO oxidized INH without exogenous hydrogen peroxide. SOD must favor reduction of oxygen by the INH radical to give superoxide and ultimately hydrogen peroxide. In both oxidation systems, an adduct with methionine was formed and it was a major product with MPO and SOD. We show that it is a conjugate of an acyldiimide with amines. INH substantially inhibited HOCl production by MPO and neutrophils below
中性粒细胞在感染个体的肺部摄取结核分枝杆菌(Mtb)。在吞噬过程中,他们使用髓过氧化物酶(MPO)催化次氯酸(HOCl)的产生,次氯酸是其最有效的抗菌剂。异烟肼(INH)是结核病治疗中最重要的抗生素,被MPO氧化。它迅速还原了MPO的化合物I [k =(1.22 +/- 0.05)x 10(6)M(-1)s(-1)],但与化合物II的反应较差[[9.8 +/- 0.6)x 10 (2)M(-1)s(-1)]。MPO和过氧化氢对INH的氧化不受化合物I的生理底物氯化物的影响,并且该酶部分转化为化合物III。这表明INH在经典的过氧化循环之外被氧化。与超氧化物歧化酶(SOD)结合使用时,MPO可以氧化INH,而无需外源过氧化氢。SOD必须有利于INH自由基还原氧,从而产生超氧化物,最终产生过氧化氢。在两个氧化系统中,都形成了蛋氨酸加合物,它是MPO和SOD的主要产物。我们表明它是酰基二酰亚胺与