STEP (Statistical Test of Equivalent Pathways) analysis: a mass spectrometric method for carbohydrates and peptides.
STEP (Statistical Test of Equivalent Pathways) analysis: a mass spectrometric method for carbohydrates and peptides.
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STEP（等效途径统计测试）分析：碳水化合物和肽的质谱方法。
DOI：
10.1021/ac050722e
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发表时间：
2005
影响因子：
7.4
通讯作者：
Desaire,Heather
中科院分区：
文献类型：
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作者：
Bandu,MaryL;Wilson,Jonathan;Vachet,RichardW;Dalpathado,DilushaS;Desaire,Heather
我们最近开发了一种新的质谱学方法，STEP(等效路径统计检验)分析，它使用两次串联质谱学实验中的离子丰度来获得质谱学中存在的产物离子的谱系信息。该方法需要最少的样品，并且可以使用传统的四极离子陷阱质谱仪进行。为了获得谱系信息，通过比较两次MS/MS实验中产物离子的相对丰度来计算阶跃比。这些比例与产物离子的来源直接相关。直接由前体离子产生的产物离子的阶跃比始终为≤1。根据具有统计学意义的aQ检验，由二次碎裂途径产生的离子的阶跃比显著大于初级离子。因此，MS/MS实验中所有产物离子的类型(初级或次级)都可以很容易地在这种分析中识别出来。本文将STEP方法应用于多肽和碳水化合物，STEP结果与本研究中95%的离子的验证数据一致。这种新方法在碳水化合物和多肽分析中有许多应用。它可用于支持多肽裂解的机理研究，并可用于区分不同异构体的碳水化合物，而不需要参考标准。给出了几个例子来证明该方法的可靠性，并提供了一个例子说明该方法如何有利于碳水化合物测序。
We have recently developed a new mass spectrometry method, the STEP (statistical test of equivalent pathways) analysis that uses ion abundances in two tandem mass spectrometry experiments to obtain genealogy information about product ions present in mass spectra. The method requires minimal sample, and it can be performed using a conventional quadrupole ion trap mass spectrometer. To obtain genealogy information, STEP ratios are calculated by comparing the relative abundances of product ions in two MS/MS experiments. These ratios are directly related to the origin of the product ions. Product ions that result directly from the precursor ion always have STEP ratios that are ≤1. Ions that result from secondary fragmentation pathways have STEP ratios that are significantly larger than the primary ions, based on aQtest of statistical significance. Consequently, the type (primary or secondary) of all the product ions in an MS/MS experiment can easily be identified in this analysis. The STEP method is applied herein to peptides and carbohydrates, and the STEP results are consistent with validation data for 95% of the ions in this study. This new method has many applications in carbohydrate and peptide analysis. It can be used to support mechanistic studies of peptide fragmentation, and it is useful for discriminating among various isomeric carbohydrates, without the need for reference standards. Several examples are presented to demonstrate the reliability of this method, and an example showing how the method benefits carbohydrate sequencing is also provided.