Modification of Tryptophan and Methionine Residues Is Implicated in the Oxidative Inactivation of Surfactant Protein B
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- 作者：Dahis Manzanares ; Karina Rodriguez-Capote ; Suya Liu ; Thomas Haines ; Yudith Ramos ; Lin Zhao ; Amanda Doherty-Kirby ; Gilles Lajoie ; Fred Possmayer
- 刊名：Biochemistry
- 出版年：2007
- 出版时间：May 8, 2007
- 年：2007
- 卷：46
- 期：18
- 页码：5604 - 5615
- 全文大小：558K
- 年卷期：v.46,no.18(May 8, 2007)
- ISSN：1520-4995
文摘
Exposing BLES (bovine lipid extract surfactant), a clinical surfactant, to reactive oxygen species(ROS) alters surfactant protein B (SP-B), as indicated by Coomassie Blue staining, silver staining, andWestern analysis. Hypochlorous acid (HOCl) treatment leads to elevated maximum surface tension (
max)and a deterioration in minimum (min) during surface area cycling. Fenton reaction resulted in immediateincreases in min and max. Intrinsic fluorescence measurements indicated Fenton, but not HOCl, inducedconversion of Trp9 of SP-B to hydroxyTrp (OHTrp), N-formylkynurenine (NFKyn), and kynurenine (Kyn).Electrospray ionization mass spectrometry (ESI-MS) revealed molecular weight alterations consistent withoxidation of Met (HOCl, Fenton) and Trp (Fenton) residues. Oxidative alterations to Met29 and Met65(HOCl, Fenton) and to Trp9 (OHTrp with HOCL and NFKyn plus Kyn with Fenton) were confirmed bymatrix-assisted laser desorption mass spectrometry (MALDI-MS) studies on SP-B tryptic fragments. SomeMet oxidation was observed with control SP-B. When taken together with captive bubble tensiometermeasurements, these studies suggest that Met oxidation of SP-B by HOCl or Fenton interferes withphospholipid respreading during compression-expansion of surfactant films, while Fenton oxidation, whichproduces more extensive Met oxidation and disruption of the indole ring of Trp9, further abrogated theability of such films to attain low surface tensions during compression. These studies provide insight intothe manner by which ROS generated during acute lung injury and the acute respiratory distress syndromeact to inhibit not only endogenous surfactant but also therapeutic surfactants administered to counteractthese conditions.
max)and a deterioration in minimum (min) during surface area cycling. Fenton reaction resulted in immediateincreases in min and max. Intrinsic fluorescence measurements indicated Fenton, but not HOCl, inducedconversion of Trp9 of SP-B to hydroxyTrp (OHTrp), N-formylkynurenine (NFKyn), and kynurenine (Kyn).Electrospray ionization mass spectrometry (ESI-MS) revealed molecular weight alterations consistent withoxidation of Met (HOCl, Fenton) and Trp (Fenton) residues. Oxidative alterations to Met29 and Met65(HOCl, Fenton) and to Trp9 (OHTrp with HOCL and NFKyn plus Kyn with Fenton) were confirmed bymatrix-assisted laser desorption mass spectrometry (MALDI-MS) studies on SP-B tryptic fragments. SomeMet oxidation was observed with control SP-B. When taken together with captive bubble tensiometermeasurements, these studies suggest that Met oxidation of SP-B by HOCl or Fenton interferes withphospholipid respreading during compression-expansion of surfactant films, while Fenton oxidation, whichproduces more extensive Met oxidation and disruption of the indole ring of Trp9, further abrogated theability of such films to attain low surface tensions during compression. These studies provide insight intothe manner by which ROS generated during acute lung injury and the acute respiratory distress syndromeact to inhibit not only endogenous surfactant but also therapeutic surfactants administered to counteractthese conditions.