title: A rapid LC-FTMS method for the analysis of cysteine, cystine and cysteine/cystine steady-state redox potential in human plasma.
abstract: BACKGROUND
  The steady-state redox potential of the cysteine/cystine couple in human plasma provides a measure of oxidative stress, yet available assays are limited by either specificity or speed of assay.
  
  
  METHODS
  The present study evaluated the use of LC-FTMS for identification based on accurate mass combined with quantification by stable isotopic dilution to rapidly determine cysteine and cystine concentration and cysteine/cystine steady-state redox potential in human plasma.
  
  
  RESULTS
  A simple extraction procedure followed by a rapid LC separation eluted cysteine in 4 min and cystine in 1.5 min with simultaneous measurement of glutathione (GSH) and glutathione disulfide (GSSG). A study of five young (mean age=25.7) subjects and 5 older (mean age=67.8 y) subjects showed an increased oxidation with age.
  
  
  CONCLUSIONS
  The analysis by LC-FTMS is suitable for high-throughput analysis of plasma cysteine, cystine and cysteine/cystine steady-state redox potential as clinical measures of oxidative stress.
authors.affiliation: Department of Medicine, Division of Pulmonary, Allergy and Critical Care, Emory University, Atlanta, GA 30322, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Johnson
authors.forename: Fredrick H
authors.initials: FH
authors.lastname: Strobel
authors.forename: Matthew
authors.initials: M
authors.lastname: Reed
authors.forename: Jan
authors.initials: J
authors.lastname: Pohl
authors.forename: Dean P
authors.initials: DP
authors.lastname: Jones
mesh_terms: D003553:Cystine / Q000097:blood* / Q000737:chemistry; D003619:Dansyl Compounds; D004220:Disulfides / Q000097:blood* / Q000737:chemistry; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D003619:Dansyl Compounds; D004220:Disulfides; D003553:Cystine; C029038:dansyl chloride