Issue 9, 2016

Accurate quantification of selenoproteins in human plasma/serum by isotope dilution ICP-MS: focus on selenoprotein P

Abstract

A species-specific isotope dilution analysis (SS IDA) method was developed for the first time for the determination of selenoprotein P (SEPP1) in human plasma/serum at the protein level by double affinity HPLC-ICP-MS. In this regard, a standard and a spike of SEPP1 were produced by cell-free E. coli protein synthesis, where Se (ICP tag) was introduced in the form of selenomethionine (SeMet) allowing for the absolute SEPP1 quantification by ICP-MS. A complete characterization of the standard and the spike was carried out in terms of isotopic composition and Se mass fraction by collision-cell ICP-MS to ensure SI-traceability. Method development and validation were conducted using the reference materials BCR-637, extensively analysed for its Se species, and the SRM 1950, which provides reference values for Se species (including SEPP1). Stability of the isotope ratio R77/76 in the sample blends was tested for one month with negligible change. Relative expanded uncertainties of 5.7% and 7.7% were achieved for BCR-637 and SRM 1950 for mass fractions of 55.5 and 63.9 ng g−1 Se for SEPP1, respectively. The developed SEPP1 SS IDA methodology could be a valuable tool to establish references values for selenoproteins in clinical chemistry and showed the potential of cell-free protein synthesis for the preparation of future stable isotope-labeled intact selenoproteins.

Graphical abstract: Accurate quantification of selenoproteins in human plasma/serum by isotope dilution ICP-MS: focus on selenoprotein P

Supplementary files

Article information

Article type
Paper
Submitted
01 Eph 2016
Accepted
26 Jul 2016
First published
26 Jul 2016

J. Anal. At. Spectrom., 2016,31, 1904-1912

Accurate quantification of selenoproteins in human plasma/serum by isotope dilution ICP-MS: focus on selenoprotein P

M. E. D. C. Busto, C. Oster, S. Cuello-Nuñez, C. L. Deitrich, A. Raab, A. Konopka, W. D. Lehmann, H. Goenaga-Infante and P. Fisicaro, J. Anal. At. Spectrom., 2016, 31, 1904 DOI: 10.1039/C6JA00122J

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