Qin J, Chait B T
Rockefeller University, New York, New York 10021, USA.
Anal Chem. 1997 Oct 1;69(19):4002-9. doi: 10.1021/ac970489n.
Matrix-assisted laser desorption/ionization (MALDI) ion trap mass spectrometry is shown to be a powerful tool for the elucidation of protein modifications. Low-energy covalent bonds that originate from certain posttranslational modifications dissociate preferentially to produce characteristic mass spectrometric signatures that prove useful for the accurate, confident identification and characterization of such modifications. Because the MALDI ion trap is an authentic tandem mass spectrometer, it proves feasible to acquire secondary information to test hypotheses as to the nature and site of the putative modifications--further increasing the reliability of the tool. The method combines the advantageous features of MALDI (i.e., the ability to measure the same sample repeatedly, to measure unfractionated complex mixtures without the need for sample cleaning, and to determine peptide mixtures with subpicomole sensitivity) with the ease and the speed of the ion trap measurement. We demonstrate how the unique properties of MALDI ion trap MS can be used to address problems involving the determination of both native posttranslational modifications of proteins (e.g., disulfide mapping, glycosylation determination, and phosphorylation determination) and non-native chemical modifications of proteins (e.g., methionine oxidation and photo-cross-linking of proteins with DNA).
基质辅助激光解吸/电离（MALDI）离子阱质谱被证明是阐明蛋白质修饰的有力工具。源自某些翻译后修饰的低能共价键优先解离，产生特征性的质谱信号，这对于准确、可靠地鉴定和表征此类修饰非常有用。由于MALDI离子阱是一种真正的串联质谱仪，获取二级信息以检验关于推定修饰的性质和位点的假设是可行的，这进一步提高了该工具的可靠性。该方法结合了MALDI的优势特性（即能够重复测量同一样品、无需样品净化即可测量未分级的复杂混合物以及以亚皮摩尔灵敏度测定肽混合物）以及离子阱测量的简便性和速度。我们展示了如何利用MALDI离子阱质谱的独特性质来解决涉及确定蛋白质天然翻译后修饰（例如二硫键图谱分析、糖基化测定和磷酸化测定）以及蛋白质非天然化学修饰（例如甲硫氨酸氧化和蛋白质与DNA的光交联）的问题。
