·OH对肌原纤维蛋白中敏感氨基酸的氧化效应分析

借助Fe3+-H2O2-Vc氧化模型体系,通过测定不同H2O2浓度条件下,氧化对肌原纤维蛋白中的氨基酸及氧化衍生物含量的影响,分析了羟自由基(·OH)对肌原纤维蛋白中敏感氨基酸的氧化效应。结果表明:·OH对构成肌原纤维蛋白氨基酸的氧化具有选择性,门冬氨酸(Asp)、甘氨酸(Gly)及亮氨酸(Leu)等对氧化作用不敏感,其含量变化不显著,而半胱氨酸(Cys)、蛋氨酸(Met)及酪氨酸(Tyr)对氧化敏感,随着H2O2浓度增加,模型体系中·OH的生成量也逐渐增加,导致3种敏感氨基酸含量呈下降趋势;对蛋白的羰基、总巯基及二酪氨酸等氧化衍生物含量的测定结果显示,氧化会导致蛋白的羰基及二酪氨酸含量增加,总巯基含量下降;进一步研究表明,氨基酸氧化存在明显的浓度效应,随着H2O2浓度升高,模型体系中·OH的生成量逐渐增加,氨基酸氧化程度加重,与未氧化的肌原纤维蛋白相比,当H2O2浓度达到20.0 mmol/L时,Cys、Met及Tyr的含量分别下降了13.3%、11.6%、20.5%。综上所述,氧化引起的含有活性基团敏感型氨基酸的结构改变是导致蛋白氧化的主要原因。

Influence of EfOM on the Oxidation of Micropollutants by Ozone and UVIH2O2 in Secondary Effluents

The aim of this work was to study the influence of effluent organic matter （EfOM） on micropollutants removal by ozone and UV/H2O2. To perform the experiments, deionized water and municipal secondary effluents （SE） were artificially contaminated with atrazine （ATZ） and treated by the two proposed methods. ATZ concentration, COD and TOC were recorded along the reaction time and used to evaluate EfOM effect on the system efficiency. Results demonstrate that the presence of EfOM can significantly reduce the micropollutant removal rate due to competition of EfOM components to react with radicals and/or molecular ozone. The hydroxyl radical scavenging caused by EfOM was quantified as well as the contribution of molecular ozone and .OH radicals during the ozonation of SE. EfOM components promoted higher inhibition of ATZ oxidation by hydroxyl radicals than by molecular ozone.