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首页> 外文学位 >Oxidation of Aromatic Amino Acids by Ferrate(VI): Kinetics and Mechanisms.
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Oxidation of Aromatic Amino Acids by Ferrate(VI): Kinetics and Mechanisms.

机译：高铁酸盐（VI）氧化芳香氨基酸的动力学和机理。

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摘要

Amino acids and proteins are an essential part of all life and are found in both biological and environmental systems. Oxidation is a major degradation pathway for proteins, and understanding how this oxidation occurs by studying individual amino acids will allow for a better overall understanding of the structure and function of proteins. The aromatic amino acids tryptophan (Trp), histidine (His), phenylalanine (Phe), and tyrosine (Tyr) are highly prone to oxidation and are the major sites of oxidative stress to proteins. Understanding how oxidative stress affects these individual aromatic amino acids can provide insight into the overall chemistry of the oxidation of proteins.;Kinetic studies of the oxidation of the aromatic amino acids by ferrate(VI) (Fe(VI), FeO42-) have been completed across the pH range 2 -- 13. The reactions all are first-order with respect to Fe(VI) and the amino acids, with the overall reaction following second-order kinetics. The second-order rate constants show a pH dependence, with Trp and Tyr rates gradually increasing from basic to acidic media, while His and Phe showed the highest rate constants in the pH range 6 -- 8.;Electron paramagnetic resonance (EPR) experiments reveal that a radical species is produced in the reactions of Fe(VI) with Trp, Phe, and His, indicating an initial 1-electron transfer step in the reaction mechanism. The reaction mechanism for the oxidation of Trp has been proposed. The identification of oxidation products was carried out using liquid chromatography-mass spectrometry (LC-MS). N-formylkynurenine (NFK) was identified as the major product of Trp oxidation at pH 7.00, indicating that an oxygen-transfer mechanism is involved after the initial 1-electron transfer step. The origin of the oxygen that is transferred to form NFK was determined to come from both the solvent of the reaction as well as directly from Fe(VI) through isotopically labeled Fe18O42- studies. The final iron species has been identified as Fe(III) through the use of Mossbauer spectroscopy and oxygen evolution experiments. The formation of Fe(III) confirms the overall 3-electron transfer of the reaction mechanism in the oxidation of Trp by Fe(VI).
机译：氨基酸和蛋白质是所有生命的重要组成部分，在生物和环境系统中都可以找到。氧化是蛋白质的主要降解途径，通过研究单个氨基酸来了解这种氧化是如何发生的，可以更好地全面理解蛋白质的结构和功能。芳香族氨基酸色氨酸（Trp），组氨酸（His），苯丙氨酸（Phe）和酪氨酸（Tyr）极易氧化，是蛋白质氧化应激的主要部位。了解氧化应激如何影响这些单个的芳香族氨基酸可以提供蛋白质氧化整体化学的见识。；高铁酸盐（VI）（Fe（VI），FeO42-）对芳香族氨基酸氧化的动力学研究已经完成。在pH范围2至13范围内完成反应。对于Fe（VI）和氨基酸而言，所有反应均为一级反应，整个反应遵循二级动力学。二阶速率常数显示pH依赖性，Trp和Tyr速率从碱性到酸性介质逐渐增加，而His和Phe在6-8的pH范围内显示最高速率常数;;电子顺磁共振（EPR）实验揭示了在Fe（VI）与Trp，Phe和His的反应中产生了自由基，这表明在反应机理中最初的1电子转移步骤。已经提出了Trp氧化的反应机理。氧化产物的鉴定使用液相色谱-质谱法（LC-MS）进行。 N-甲酰基肾上腺素（NFK）被确定为pH 7.00时Trp氧化的主要产物，表明在最初的1电子转移步骤之后涉及了氧转移机制。已确定转移形成NFK的氧的来源既来自反应的溶剂，也来自同位素同位素标记的Fe18O42-直接来自Fe（VI）。通过使用Mossbauer光谱法和氧气析出实验，最终的铁物种已鉴定为Fe（III）。 Fe（III）的形成证实了Fe（VI）氧化Trp时反应机理的整体3电子转移。

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  • 作者

    Casbeer, Erik Michael.;

  • 作者单位

    Florida Institute of Technology.;

  • 授予单位 Florida Institute of Technology.;
  • 学科 Chemistry Analytical.;Chemistry Biochemistry.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 191 p.
  • 总页数 191
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农学（农艺学）;
  • 关键词

  • 入库时间 2022-08-17 11:42:32

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