Strategy for absolute quantification of proteins: CH3Hg+labeling integrated molecular and elemental mass spectrometry

Yifei Guo; Ming Xu; Limin Yang; Qiuquan Wang

doi:10.1039/B902241D

Strategy for absolute quantification of proteins: CH₃Hg⁺labeling integrated molecular and elemental mass spectrometry†‡

Yifei Guo,^a Ming Xu,^a Limin Yang^a and Qiuquan Wang*^ab

* Corresponding authors

^a Department of Chemistry & the MOE Key Laboratory of Modern Analytical Sciences, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
E-mail: qqwang@xmu.edu.cn
Fax: +86 592 2187400
Tel: +86 592 2181796

^b State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China

Abstract

Currently, molecular mass spectrometry is preferred by many for relative quantification but is not appropriate for “absolute” quantification of proteins. In this article we demonstrate a proof of concept for the absolute quantitative analysis of proteinsvia CH₃Hg⁺labeling and integrated application of molecular and elemental mass spectrometry. The smallest size of CH₃Hg⁺ among monoalkyl mercurials and the specific and covalent interaction with sulfhydryl (–SH) in proteins results in forming a simple complex of CH₃Hg⁺:–SH = 1:1 when all –SH are exposed, as confirmed by ESI-MS. Based on the known number of –SH per protein, the absolute protein concentration can be obtained viaHg determination using ICP-MS, in which CH₃HgCl could be simply used as an external standard. When bovine pancreatic ribonuclease A, lysozyme and insulin, which have an increasing number of various disulfide linkages in their molecules, were taken as model proteins, their corresponding absolute detection limits (3σ) reached 0.6, 1.2 and 0.4 pmol, respectively. These characteristics may be expected to provide an alternative approach for absolute protein quantification, especially specific biomarker determination, in the near future.

This article is part of the themed collection: Third Asia-Pacific Winter Conference on Plasma Spectrochemistry, Tsukuba, Japan

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Article information

DOI: https://doi.org/10.1039/B902241D
Article type: Technical Note
Submitted: 03 Feb 2009
Accepted: 21 Jul 2009
First published: 27 Jul 2009

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J. Anal. At. Spectrom., 2009,24, 1184-1187

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Strategy for absolute quantification of proteins: CH₃Hg⁺labeling integrated molecular and elemental mass spectrometry

Y. Guo, M. Xu, L. Yang and Q. Wang, J. Anal. At. Spectrom., 2009, 24, 1184 DOI: 10.1039/B902241D

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Journal of Analytical Atomic Spectrometry