Absolute Quantitation of Oxidizable Peptides by Coulometric Mass Spectrometry
Absolute Quantitation of Oxidizable Peptides by Coulometric Mass Spectrometry
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DOI：
10.1007/s13361-019-02299-z
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发表时间：
2019-11-01
影响因子：
3.2
通讯作者：
Chen，Hao
中科院分区：
文献类型：
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作者：
Zhao，Pengyi;Zare，Richard N.;Chen，Hao
使用质谱法的肽的定量方法发展迅速。这些方法依赖于使用标准和/或同位素标记的肽，其合成可能是困难或昂贵的。为了应对这一挑战，我们提出了一种新的方法，用于绝对定量，而不使用标准品或校准曲线的基础上库仑法结合质谱法（MS）。在这种方法中，我们称之为库仑质谱法（CMS），含有一个或多个酪氨酸残基的目标肽的质谱在经历电化学氧化之前和之后被记录。我们记录来自电化学测量的总积分氧化电流，其根据库仑法的法拉第定律提供氧化肽的摩尔数。氧化前后靶肽的离子强度比提供了对已被氧化的肽的分数的极好估计，由此计算肽的总量。CMS的显著优势在于它不需要标准肽，但CMS确实要求肽含有已知数量的可氧化基团。为了说明这种方法的功效，我们分析了各种含酪氨酸的肽，如GGYR，DRVY，催产素，[Arg 8]-催产素和血管紧张素原1-14，定量误差范围为-7.5%至2.4%。这种方法也适用于定量磷酸肽，并可能是有用的蛋白质组学研究。
Quantitation methods for peptides using mass spectrometry have advanced rapidly. These methods rely on using standard and/or isotope-labeled peptides, which might be difficult or expensive to synthesize. To tackle this challenge, we present a new approach for absolute quantitation without the use of standards or calibration curves based on coulometry combined with mass spectrometry (MS). In this approach, which we call coulometric mass spectrometry (CMS), the mass spectrum of a target peptide containing one or more tyrosine residues is recorded before and after undergoing electrochemical oxidation. We record the total integrated oxidation current from the electrochemical measurement, which according to the Faraday’s Law of coulometry, provides the number of moles of oxidized peptide. The ion intensity ratio of the target peptide before and after oxidation provides an excellent estimate of the fraction of the peptide that has been oxidized, from which the total amount of peptide is calculated. The striking strength of CMS is that it needs no standard peptide, but CMS does require the peptide to contain a known number of oxidizable groups. To illustrate the power of this method, we analyzed various tyrosine-containing peptides such as GGYR, DRVY, oxytocin, [Arg8]-vasotocin and angiotensinogen 1–14 with a quantification error ranging from − 7.5 to + 2.4%. This approach is also applicable to quantifying phosphopeptides and could be useful in proteomics research.