In this work, chemical dynamics simulations were optimized and used to predict fragmentation mass spectra for DNA adduct structural determination. O6-methylguanine (O6-Me-G) was used as a simple model adduct to calculate theoretical spectra for comparison with measured high-resolution fragmentation data. An automatic protocol was established to consider the different tautomers accessible at a given energy and obtain final theoretical spectra by insertion of an initial tautomer. In the work reported here, the most stable tautomer was chosen as the initial structure, but in general, any structure could be considered. Allowing for the formation of the various possible tautomers during simulation calculations was found to be important to getting a more complete fragmentation spectrum. The calculated theoretical results reproduce the experimental peaks such that it was possible to determine reaction pathways and product structures. The calculated tautomerization network was crucial to correctly identifying all the observed ion peaks, showing that a mobile proton model holds not only for peptide fragmentation but also for nucleobases. Finally, first principles results were compared to simple machine learning fragmentation models.

中文翻译：

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碎片光谱预测和DNA加合物的结构测定。

在这项工作中，化学动力学模拟得到优化，并用于预测DNA加合物结构测定的碎片质谱。O6-甲基鸟嘌呤（O6-Me-G）被用作简单的模型加合物来计算理论光谱，以便与测得的高分辨率碎片数据进行比较。建立了自动方案以考虑在给定能量下可及的不同互变异构体，并通过插入初始互变异构体获得最终的理论光谱。在本文报道的工作中，最稳定的互变异构体被选为初始结构，但通常可以考虑任何结构。发现在模拟计算期间允许形成各种可能的互变异构体对于获得更完整的碎片光谱很重要。计算出的理论结果重现了实验峰，因此可以确定反应途径和产物结构。计算的互变异构网络对于正确识别所有观察到的离子峰至关重要，这表明移动质子模型不仅适用于肽片段化，而且适用于核碱基。最后，将第一个原理的结果与简单的机器学习碎片模型进行了比较。