Oxidation of amino acids by peracetic acid: Reaction kinetics, pathways and theoretical calculations
Oxidation of amino acids by peracetic acid: Reaction kinetics, pathways and theoretical calculations
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DOI：
10.1016/j.wroa.2018.09.002
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发表时间：
2018-12-01
期刊：
影响因子：
7.5
通讯作者：
Huang, Ching-Hua
中科院分区：
文献类型：
--
作者：
Du, Penghui;Liu, Wen;Huang, Ching-Hua
过氧乙酸（PAA）是一种在食品、医疗和水处理行业中使用越来越多的消毒剂。氨基酸是PAA处理的目标食品中的重要组分，并且作为溶解有机氮的主要形式普遍存在于天然水体和废水中。为了更好地理解可能的反应，本工作研究了所选氨基酸向PAA的反应动力学和转化途径。实验结果表明，除了半胱氨酸（CYS）、蛋氨酸（MET）和组氨酸（HIS）外，大多数氨基酸对PAA反应迟钝。CYS表现出最高的反应性，反应速率非常快。MET和HIS与PAA的反应遵循二级动力学，在pH 7下的速率常数分别为4.6 +/- 0.2和1.8 +/- 0.1 M-1.s（-1）。由于PAA形态形成，在pH 5和7下的反应比在pH 9下更快。低浓度H_2O_2与PAA共存时，对氨基酸的氧化作用不大。PAA氧化氨基酸的主要产物是巯基、硫醚基和咪唑基上的[O]加成物。理论计算被应用于预测PAA亲电攻击氨基酸的反应性和区域选择性，并提高了对机理的理解。作为一种氧化性消毒剂，PAA与有机物反应形成副产物是不可避免的;然而，这项研究表明，PAA对生物分子（如氨基酸）的反应性比其他常见消毒剂更低，选择性更强，因此对有毒消毒副产物的关注较少。该属性可以允许PAA在各种应用中的更大的稳定性和更有针对性的作用。(C)2018由Elsevier Ltd.出版
Peracetic acid (PAA) is a sanitizer with increasing use in food, medical and water treatment industries. Amino acids are important components in targeted foods for PAA treatment and ubiquitous in natural waterbodies and wastewater effluents as the primary form of dissolved organic nitrogen. To better understand the possible reactions, this work investigated the reaction kinetics and transformation pathways of selected amino acids towards PAA. Experimental results demonstrated that most amino acids showed sluggish reactivity to PAA except cysteine (CYS), methionine (MET), and histidine (HIS). CYS showed the highest reactivity with a very rapid reaction rate. Reactions of MET and HIS with PAA followed second-order kinetics with rate constants of 4.6 +/- 0.2, and 1.8 +/- 0.1 M-1.s(-1) at pH 7, respectively. The reactions were faster at pH 5 and 7 than at pH 9 due to PAA speciation. Low concentrations of H2O2 coexistent with PAA contributed little to the oxidation of amino acids. The primary oxidation products of amino acids with PAA were [O] addition compounds on the reactive sites at thiol, thioether and imidazole groups. Theoretical calculations were applied to predict the reactivity and regioselectivity of PAA electrophilic attacks on amino acids and improved mechanistic understanding. As an oxidative disinfectant, the reaction of PAA with organics to form byproducts is inevitable; however, this study shows that PAA exhibits lower and more selective reactivity towards biomolecules such as amino acids than other common disinfectants, causing less concern of toxic disinfection byproducts. This attribute may allow greater stability and more targeted actions of PAA in various applications. (C) 2018 Published by Elsevier Ltd.