Absolute Quantitation of Tryptophan-Containing Peptides and Amyloid β-Peptide Fragments by Coulometric Mass Spectrometry

• DOI: 10.1021/jasms.1c00121
• Publication Date: 2021-06-08T19:03:02Z
• Authors: Yongling Ai; Pengyi Zhao; Praneeth Ivan Joe...; Hao Chen
• Keywords: Isotope dilution; Coulometry

Isotope-labeled internal standards are routinely used for mass spectrometry (MS)-based absolute quantitation. However, syntheses of isotope-labeled peptides time-consuming and costly. To tackle this issue, we recently developed a coulometric spectrometric (CMS) approach quantitation without the use standards, based on electrochemical oxidation cysteine or tyrosine-containing followed by measurement yield. further expand utility method, herein present CMS method tryptophan oxidation. Several tryptophan-containing peptides, such as WGG, WQPPRARI, WAGGDASGE, RTRPLWVRME, KVPRNQDWL, were successfully quantified with quantification error ranging from -4.5 to +4.3%. Furthermore, is also applicable protein, in which protein can be digested surrogate peptide selected reflect amount parent exemplified analysis GITWK cytochrome c. The result agreed well traditional isotope dilution only small difference 3.5%. In addition, was quantify amyloid beta (Aβ) fragments (up 28 amino acid residues) tyrosine validity using would greatly facilitate proteomics research.