Virelizier H, Hagemann R, Jankowski K
Biomed Mass Spectrom. 1983 Oct;10(10):559-66. doi: 10.1002/bms.1200101006.
The positive ion and negative ion pyrolysis mass spectra of the herring sperm DNA have been studied using desorption chemical ionization. The positive ion desorption chemical ionization spectra have been produced with CH4, i-C4H10, NH3, HCl and Cl2; the negative ones with N2O/CH4, N2O/i-C4H10, Cl2, CCl4, HCl and via electron capture. These spectra have been compared with the electron impact ionization spectra. We have observed an important increase of sensitivity when negative ionization has replaced the positive ionization mode. The series of diagnostic ions resulting from direct chemical ionization belong to the family of base + reagent ion X [BH + X] and base + X - HX ion [B]. Their abundance has increased considerably compared to the electron impact spectra. The application of these new diagnostic ions in nucleic acid studies is interesting especially for the much higher abundance of the usually weak dG fragment ion obtained in the negative ionization mode. The dG-base segment of the DNA is the most nucleophilic centre of the whole nucleic acid and is implicated in numerous important biochemical reactions involving, for example, proteins.
利用解吸化学电离研究了鲱鱼精DNA的正离子和负离子热解质谱。正离子解吸化学电离谱是用CH4、异丁烷、NH3、HCl和Cl2产生的；负离子解吸化学电离谱是用N2O/CH4、N2O/异丁烷、Cl2、CCl4、HCl并通过电子捕获产生的。这些谱图与电子轰击电离谱进行了比较。我们观察到当负离子化取代正离子化模式时灵敏度有显著提高。直接化学电离产生的一系列诊断离子属于碱 + 试剂离子X [BH + X]和碱 + X - HX离子[B]家族。与电子轰击谱相比，它们的丰度有了显著增加。这些新的诊断离子在核酸研究中的应用很有趣，特别是因为在负离子化模式下获得的通常较弱的dG碎片离子的丰度要高得多。DNA的dG碱基片段是整个核酸中最具亲核性的中心，并且参与许多重要的生化反应，例如涉及蛋白质的反应。
