Gabig T G, Lefker B A, Ossanna P J, Weiss S J
J Biol Chem. 1984 Nov 10;259(21):13166-71.
Control of the intraphagosomal pH in neutrophils may be of importance in creating a microbicidal environment by regulating the activity of the O2-.-generating NADPH oxidase and the lysosomal enzymes discharged into this compartment. In this study, we examined the proton stoichiometry associated with the primary enzymatic reaction underlying the respiratory burst. A preparation of the neutrophil-derived, membrane oxidase consumed NADPH and generated O2-. with a stoichiometry of 1 NADPH:2 O2-. When the enzymatically produced O2-. was prevented from undergoing dismutation, net protons were released in an approximate 1:2 stoichiometry with O2-. generated. In contrast, when O2-. was allowed to dismutate to H2O2, net protons were consumed in a 1:1 stoichiometry with the accumulated H2O2. Thus, the delta pH associated with the NADPH oxidase-dependent production of O2-. was dictated by the fate of the generated radical. The consumption of the oxidase-generated H2O2 by the lysosomal enzyme myeloperoxidase resulted in the formation of HOCl which was trapped in the presence of taurine as the N-chloro derivative. The ratio of chlorinated product formed to H+ consumed was 1:1. The implications of these results are discussed in terms of the known intraphagosomal pH changes that occur following neutrophil stimulation. We conclude that the O2-.-generating oxidase plays a dual role in the phagosome by simultaneously creating an oxidizing environment that optimizes pH-dependent microbicidal processes.
控制中性粒细胞内吞噬体的pH值对于通过调节产氧的NADPH氧化酶和释放到该区室的溶酶体酶的活性来创造杀菌环境可能很重要。在本研究中，我们研究了与呼吸爆发基础的初级酶促反应相关的质子化学计量。一种源自中性粒细胞的膜氧化酶制剂消耗NADPH并产生O2-，化学计量为1个NADPH：2个O2-。当酶促产生的O2-不发生歧化反应时，净质子以与产生的O2-近似1:2的化学计量释放。相反，当O2-发生歧化反应生成H2O2时，净质子以与积累的H2O2 1:1的化学计量被消耗。因此，与依赖NADPH氧化酶产生O2-相关的ΔpH值取决于所产生自由基的命运。溶酶体酶髓过氧化物酶消耗氧化酶产生的H2O2导致形成HOCl，在牛磺酸存在下HOCl以N-氯衍生物的形式被捕获。形成的氯化产物与消耗的H+的比例为1:1。根据中性粒细胞刺激后已知的吞噬体内pH值变化讨论了这些结果的意义。我们得出结论，产O2-的氧化酶在吞噬体中起双重作用，同时创造一个优化pH依赖性杀菌过程的氧化环境。
