Mass measurement accuracy in analyses of highly complex mixtures based upon multidimensional recalibration
Mass measurement accuracy in analyses of highly complex mixtures based upon multidimensional recalibration
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DOI：
10.1021/ac0606251
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发表时间：
2006-12-15
影响因子：
7.4
通讯作者：
Smith, Richard D.
中科院分区：
文献类型：
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作者：
Tolmachev, Aleksey V.;Monroe, Matthew E.;Smith, Richard D.
质谱结合一系列在线分离技术已成为表征复杂混合物的有力工具，包括蛋白质组学研究中的蛋白质组学。由于在线分离过程中发生的变化，准确的质量测量可能会受到影响，例如。例如，在一个实施例中，这是由于离子阱中过量的空间电荷、温度变化或仪器“漂移”的其它来源。我们已经开发了一种多维重新校准方法，该方法利用关于可能的混合物组成的现有信息，考虑质量测量的可变条件，并且校正由例如质谱的总离子计数、单个峰丰度、m/z值和液相色谱分离时间分组的单个峰的集合的质量校准。多维重新校准方法使用在这样的测量中测量的质量（通常超过105）与可能存在于混合物中的大量推定的已知物质（即，具有已知的精确质量），以鉴定用作有效校准物的检测物质的子集。重新校准程序涉及质量准确度分布（直方图）的优化，以提供真假鉴定之间更可靠的区分。我们报告了使用TOF和几个FTICR质谱仪获得的数据的质量精度提高。我们表明，多维重新校准更好地补偿了系统质量测量误差，也显着降低了质量误差扩散：即，质量测量的准确度和精确度都得到提高。质量测量的改善被发现是几乎独立的初始仪器校准，允许，例如，不太频繁的校准。我们表明，这种重新校准可以提供亚ppm的质量测量精度的测量一个复杂的真菌蛋白质组胰蛋白酶消化，并提供改进的信心或肽鉴定的数量。
Mass spectrometry combined with a range of on-line separation techniques has become a powerful tool for characterization of complex mixtures, including protein digests in proteomics studies. Accurate mass measurements can be compromised due to variations that occur in the course of an on-line separation, e. g., due to excessive space charge in an ion trap, temperature changes, or other sources of instrument "drift". We have developed a multidimensional recalibration approach that utilizes existing information on the likely mixture composition, taking into account variable conditions of mass measurements, and that corrects the mass calibration for sets of individual peaks binned by, for example, the total ion count for the mass spectrum, the individual peak abundance, m/z value, and liquid chromatography separation time. The multidimensional recalibration approach uses a statistical matching of measured masses in such measurements, often exceeding 105, to a significant number of putative known species likely to be present in the mixture (i.e., having known accurate masses), to identify a subset of the detected species that serve as effective calibrants. The recalibration procedure involves optimization of the mass accuracy distribution ( histogram), to provide a more confident distinction between true and false identifications. We report the mass accuracy improvement obtained for data acquired using a TOF and several FTICR mass spectrometers. We show that the multidimensional recalibration better compensates for systematic mass measurement errors and also significantly reduces the mass error spread: i.e., both the accuracy and precision of mass measurements are improved. The mass measurement improvement is found to be virtually independent of the initial instrument calibration, allowing, for example, less frequent calibration. We show that this recalibration can provide sub-ppm mass measurement accuracy for measurements of a complex fungal proteome tryptic digest and provide improved confidence or numbers of peptide identifications.