Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
Department of Chemistry, Towson University, Towson, Maryland 21252, United States.
Environ Sci Technol. 2022 Sep 20;56(18):13347-13356. doi: 10.1021/acs.est.2c03267. Epub 2022 Aug 26.
Free available chlorine (FAC) is widely used to inactivate viruses by oxidizing viral components, including genomes. It is commonly assumed that hypochlorous acid (HOCl) is the chlorinating agent responsible for virus inactivation; however, recent studies have underscored that minor constituents of FAC existing in equilibrium with HOCl, such as molecular chlorine (Cl), can influence FAC reactivity toward select organic compounds. This study measures the FAC reaction kinetics with dsDNA and ssDNA extracted from representative bacteriophages (T3 and ϕX174) in samples augmented with chloride. Herein, chloride enhances FAC reactivity toward dsDNA and, to a lesser extent, toward ssDNA, especially at pH < 7.5. The enhanced reactivity can be attributed to the formation of Cl. Second-order rate constants were determined for reactions of ssDNA and dsDNA with HOCl and Cl. DNA chlorination kinetics followed the reactivity-selectivity principle, where the more-reactive nucleophilic species (ssDNA, ∼100× more reactive than dsDNA) reacted less selectively with electrophilic FAC species. The addition of chloride was also shown to enhance the inactivation of bacteriophage T3 (dsDNA genome) by FAC but did not enhance the inactivation of bacteriophage ϕX174 (ssDNA genome). Overall, the results suggest that Cl is an important chlorinating agent of nucleic acids and viruses.
游离有效氯（FAC）通过氧化病毒成分，包括基因组，被广泛用于灭活病毒。人们通常认为次氯酸（HOCl）是导致病毒失活的氯化剂；然而，最近的研究强调了 FAC 与 HOCl 处于平衡状态的次要成分，如分子氯（Cl），会影响 FAC 对某些有机化合物的反应性。本研究在添加氯的样品中测量了从代表性噬菌体（T3 和 ϕX174）中提取的双链 DNA（dsDNA）和单链 DNA（ssDNA）与 FAC 的反应动力学。在此，氯离子增强了 FAC 对 dsDNA 的反应性，并且在 pH < 7.5 时对 ssDNA 的反应性也有所增强。增强的反应性可归因于 Cl 的形成。确定了 HOCl 和 Cl 与 ssDNA 和 dsDNA 的反应的二级速率常数。DNA 氯化动力学遵循反应选择性原理，其中更具反应性的亲核物种（ssDNA，比 dsDNA 反应性高约 100 倍）与亲电 FAC 物种的反应选择性较低。还表明氯离子的添加增强了 FAC 对噬菌体 T3（dsDNA 基因组）的灭活作用，但并未增强噬菌体 ϕX174（ssDNA 基因组）的灭活作用。总体而言，结果表明 Cl 是核酸和病毒的重要氯化剂。
