Rapid analysis of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) isotopologues in stable isotope-resolved metabolomics (SIRM) using direct infusion nanoelectrospray ultra-high-resolution Fourier transform mass spectrometry (DI-nESI-UHR-FTMS)

Anal Chim Acta. 2021 Oct 9:1181:338873. doi: 10.1016/j.aca.2021.338873. Epub 2021 Jul 26.

Abstract

S-Adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are important metabolites in the one-carbon cycle that modulates cellular methylation required for proliferation and epigenetic regulation. Their concentrations, synthesis, and turnover are difficult to determine conveniently and reliably. We have developed such a method by coupling a simple and rapid purification scheme that efficiently captures both compounds, with high sensitivity, sample throughput direct infusion nanoelectrospray ultra-high-resolution Fourier transform mass spectrometry (DI-nESI-UHR-FTMS). This method is compatible with Stable Isotope-Resolved Metabolomic (SIRM) analysis of numerous other metabolites. The limits of detection for both SAM and SAH were <1 nM, and the linearity range was up to 1000 nM. The method was first illustrated for SAM/SAH analysis of mouse livers, and lung adenocarcinoma A549 cells. We then applied the method to track 13C1-CH3-Met incorporation into SAM and 13C6-glucose transformation into SAM and SAH via de novo synthesis. We further used the method to show the distinct effects on A549 and H1299 cells with treatment of anti-cancer methylseleninic acid (MSA), selenite, and selenomethionine, notably SAM depletion and increased SAM to SAH ratio by MSA, which implicates altered epigenetic regulation.

Keywords: DI-nESI-UHR-FTMS; Methylseleninic acid; S-adenosylhomocysteine; S-adenosylmethionine; Selenite; Stable isotope-resolved metabolomics.

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Animals
  • Epigenesis, Genetic
  • Fourier Analysis
  • Isotopes
  • Mass Spectrometry
  • Metabolomics
  • Mice
  • S-Adenosylhomocysteine*
  • S-Adenosylmethionine*

Substances

  • Adaptor Proteins, Signal Transducing
  • Ftm protein, mouse
  • Isotopes
  • S-Adenosylmethionine
  • S-Adenosylhomocysteine