OH-Radical Oxidation of Lung Surfactant Protein B on Aqueous Surfaces
OH-Radical Oxidation of Lung Surfactant Protein B on Aqueous Surfaces
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DOI：
10.5702/massspectrometry.s0077
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发表时间：
2018-11
影响因子：
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通讯作者：
Shinichi Enami;A. Colussi
中科院分区：
文献类型：
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作者：
Shinichi Enami;A. Colussi
空气污染物会在肺表面产生活性氧物种。本文报道了注入到水表面的羟基自由基(·OH)与人肺表面活性蛋白B的25个残基多肽替代物SP-B1-25的反应。我们的实验包括SP-B1-25水溶液与O_3/O_2/H_2O/N_2(G)气流相交的微射流，这些气流在266 nm的激光纳秒脉冲下原位光解为·OH(G)。表面敏感质谱仪使我们能够监测由·OH与界面SP-B1-25反应引发的初级含氧产物/中间体的即时(<；10μS)和同时生成(n≤5)。我们发现，在SP-B1-25的疏水N-末端的反应性半胱氨酸Cys8和Cys11以及色氨酸Trp9组分中都加入了来自臭氧和·OH的O-原子，该末端位于气液界面的最顶层。值得注意的是，这些过程是由·OH加成开始的，而不是由S-H、C-H或N-H基团中的H原子提取引起的。通过增加SP-B1-25的N-末端区域的亲水性，这些转变将削弱其作为表面活性物质的作用。
Air pollutants generate reactive oxygen species on lung surfaces. Here we report how hydroxyl radicals (·OH) injected on the surface of water react with SP-B1–25, a 25-residue polypeptide surrogate of human lung surfactant protein B. Our experiments consist of intersecting microjets of aqueous SP-B1–25 solutions with O3/O2/H2O/N2(g) gas streams that are photolyzed into ·OH(g) in situ by 266 nm laser nanosecond pulses. Surface-sensitive mass spectrometry enables us to monitor the prompt (<10 μs) and simultaneous formation of primary On-containing products/intermediates (n≤5) triggered by the reaction of ·OH with interfacial SP-B1–25. We found that O-atoms from both O3 and ·OH are incorporated into the reactive cysteine Cys8 and Cys11 and tryptophan Trp9 components of the hydrophobic N-terminus of SP-B1–25 that lies at the topmost layers of the air–liquid interface. Remarkably, these processes are initiated by ·OH additions rather than by H-atom abstractions from S–H, C–H, or N–H groups. By increasing the hydrophilicity of the N-terminus region of SP-B1–25, these transformations will impair its role as a surfactant.