Journal article

Isotope dilution gas chromatography/mass spectrometry method for the determination of methionine sulfoxide in protein

MA Sochaski, AJ Jenkins, TJ Lyons, SR Thorpe, JW Baynes

ANALYTICAL CHEMISTRY | AMER CHEMICAL SOC | Published : 2001

Abstract

We have developed a new technique for quantifying methionine sulfoxide (MetSO) in protein to assess levels of oxidative stress in physiological systems. In this procedure, samples are hydrolyzed with methanesulfonic acid (MSA) in order to avoid the conversion of MetSO to methionine (Met) that occurs during hydrolysis of protein in HCl. The hydrolysate is fractionated on a cation exchange column to remove the nonvolatile MSA from amino acids, and the amino acids are then derivatized as their trimethylsilyl esters for analysis by selected ion monitoring-gas chromatography/mass spectrometry. The limit of detection of the assay is 200 pmol of MetSO per analysis, and the interassay coefficient of..

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