Absolute Quantitation of Oxidizable Peptides by Coulometric Mass Spectrometry

Document Type

Article

Publication Date

11-1-2019

Abstract

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. [Figure not available: see fulltext.].

Identifier

85071276432 (Scopus)

Publication Title

Journal of the American Society for Mass Spectrometry

External Full Text Location

https://doi.org/10.1007/s13361-019-02299-z

e-ISSN

18791123

ISSN

10440305

PubMed ID

31429055

First Page

2398

Last Page

2407

Issue

11

Volume

30

Grant

1915878

Fund Ref

National Science Foundation

This document is currently not available here.

Share

COinS