Center of Mass Calculation in Combination with MS/MS Allows Robust Identification of Single Amino Acid Polymorphisms in Clinical Measurements of Insulin-Like Growth Factor-1

Anthony Maus, Jennifer Kemp, Dragana Milosevic, Santosh Renuse, Akhilesh Pandey, Ravinder J. Singh, Stefan K.G. Grebe

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Insulin-like growth factor-1 (IGF-1) measurement by high-resolution accurate mass-mass spectrometry (HRAM-MS) is replacing IGF-1 immunoassays and allows for identification of single amino acid variants; by contrast, both normal and deleterious sequence variants might be missed by immunoassays or non-HRAM-MS methods. We have developed an intact molecule HRAM-MS method to identify IGF-1 variants, distinguishing them by a center of mass (COM) calculation, followed by various tandem-MS activation techniques (HCD, ETD, ETciD, EThcD, UVPD). We found single amino acid variants in 841 of 146 620 patient samples (0.57%). Most were benign (A67T, A70T). We also observed a pathogenic variant (V44M), likely pathogenic variants (A38V, V17M), and a likely benign variant (A67V). For 207 samples from unique patients with residual serum, the MS variant results were confirmed by cell-free DNA sequencing. Our approach allows accurate quantitative reporting of functional IGF-1 in the presence of single amino acid variants. The COM approach potentially enables omission of tandem-MS for known, common variants, while the combination of COM and tandem-MS allows accurate identification in all cases we encountered. This approach should be applicable to qualitative and quantitative analyses of other peptides/proteins in clinical and research settings and might lend itself to the characterization of other protein variations.

Original languageEnglish (US)
Pages (from-to)186-193
Number of pages8
JournalJournal of Proteome Research
Volume19
Issue number1
DOIs
StatePublished - Jan 3 2020

Keywords

  • center of mass calculation
  • high-resolution accurate mass-MS
  • insulin-like growth factor-1
  • intact molecule MS
  • single amino acid protein variants
  • tandem mass spectrometry

ASJC Scopus subject areas

  • Biochemistry
  • Chemistry(all)

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