Cheluvappa Rajkumar, Shimmon Ronald, Dawson Michael, Hilmer Sarah N, Le Couteur David G
Centre for Education and Research on Ageing and ANZAC Research Institute, University of Sydney and Concord RG Hospital, Concord, Australia.
Acta Biochim Pol. 2008;55(3):571-80. Epub 2008 Sep 17.
Pseudomonas aeruginosa is the most common cause of chronic and recurrent lung infections in patients with cystic fibrosis (CF) whose sputa contain copious quantities of P. aeruginosa toxin, pyocyanin. Pyocyanin triggers tissue damage mainly by its redox cycling and induction of reactive oxygen species (ROS). The reactions between reduced glutathione (GSH) and pyocyanin were observed using absorption spectra from spectrophotometry and the reaction products analysed by nuclear magnetic resonance imaging. Pyocyanin reacted with GSH non-enzymatically at 37 degrees C resulting in the production of red-brown products, spectophotometrically visible as a 480 nm maximum absorption peak after 24 h of incubation. The reaction was concentration-dependent on reduced glutathione but not on pyocyanin. Minimizing the accessibility of oxygen to the reaction decreased its rate. The anti-oxidant enzyme catalase circumvented the reaction. Proton-NMR analysis demonstrated the persistence of the original aromatic ring and the methyl-group of pyocyanin in the red-brown products. Anti-oxidant agents having thiol groups produced similar spectophotometrically visible peaks. The presence of a previously unidentified non-enzymatic GSH-dependent metabolic pathway for pyocyanin has thus been identified. The reaction between pyocyanin and GSH is concentration-, time-, and O(2)-dependent. The formation of H(2)O(2) as an intermediate and the thiol group in GSH seem to be important in this reaction.
铜绿假单胞菌是囊性纤维化（CF）患者慢性和复发性肺部感染的最常见病因，这些患者的痰液中含有大量铜绿假单胞菌毒素——绿脓菌素。绿脓菌素主要通过其氧化还原循环和诱导活性氧（ROS）来引发组织损伤。利用分光光度法的吸收光谱观察了还原型谷胱甘肽（GSH）与绿脓菌素之间的反应，并通过核磁共振成像分析了反应产物。绿脓菌素在37℃下与GSH发生非酶反应，生成红棕色产物，孵育24小时后，分光光度法可见其在480nm处有最大吸收峰。该反应的速率取决于还原型谷胱甘肽的浓度，而不取决于绿脓菌素的浓度。减少反应体系中的氧气可降低反应速率。抗氧化酶过氧化氢酶可抑制该反应。质子核磁共振分析表明，红棕色产物中仍保留有绿脓菌素的原始芳香环和甲基。具有巯基的抗氧化剂也产生了类似的分光光度法可见峰。因此，已确定存在一种以前未被识别的绿脓菌素非酶依赖GSH的代谢途径。绿脓菌素与GSH之间的反应取决于浓度、时间和氧气。H₂O₂作为中间产物的形成以及GSH中的巯基在该反应中似乎很重要。
