Department of Civil and Environmental Engineering , University of Michigan , Ann Arbor , Michigan 48109 , United States.
Environ Sci Technol. 2018 Sep 18;52(18):10408-10415. doi: 10.1021/acs.est.8b02308. Epub 2018 Aug 24.
Determining the influence of higher order structure on UVC photolysis will help inform predictions of nucleic acid fate and microorganism inactivation. We measured the direct UV photolysis kinetics of four model viral genomes composed of single-stranded and double-stranded RNA (ssRNA and dsRNA, respectively), as well as single-stranded and double-stranded DNA (ssDNA and dsDNA, respectively), in ultrapure water, in phosphate buffered saline (PBS), and encapsidated in their native virus particles. The photolysis rate constants of naked nucleic acids measured by qPCR (RT-qPCR for RNA) and normalized by the number of bases measured in a particular sequence exhibited the following trend: ssDNA > ssRNA ≈ dsDNA > dsRNA. In PBS, naked ssRNA bases reacted, on average, 24× faster than the dsRNA bases, whereas naked ssDNA bases reacted 4.3× faster than dsDNA bases. Endogenous indirect photolysis involving O and ·OH was ruled out as a major contributing factor in the reactions. A comparison of our measured rate constants with rate constants reported in the literature shows a general agreement among the nucleic acid UV direct photolysis kinetics. Our results underscore the high resistance of dsRNA to UVC photolysis and demonstrate the role that nucleic acid structure and solution chemistry play in photoreactivity.
确定高级结构对 UVC 光解的影响将有助于预测核酸的命运和微生物的失活。我们测量了由单链和双链 RNA（ssRNA 和 dsRNA，分别）以及单链和双链 DNA（ssDNA 和 dsDNA，分别）组成的四种模型病毒基因组在超纯水中、磷酸盐缓冲盐溶液（PBS）中和封装在其天然病毒颗粒中的直接 UV 光解动力学。通过 qPCR（RNA 的 RT-qPCR）测量并通过特定序列中测量的碱基数归一化的裸露核酸的光解速率常数表现出以下趋势：ssDNA>ssRNA≈dsDNA>dsRNA。在 PBS 中，裸露的 ssRNA 碱基的反应速度平均比 dsRNA 碱基快 24 倍，而裸露的 ssDNA 碱基的反应速度比 dsDNA 碱基快 4.3 倍。排除了涉及 O 和·OH 的内源性间接光解作为反应中的主要贡献因素。将我们测量的速率常数与文献中报道的速率常数进行比较表明，核酸 UV 直接光解动力学之间具有普遍的一致性。我们的结果强调了 dsRNA 对 UVC 光解的高抗性，并证明了核酸结构和溶液化学在光反应性中的作用。
