title: Detection of oxidized and glycated proteins in clinical samples using mass spectrometry--a user's perspective.
abstract: BACKGROUND
  Proteins in human tissues and body fluids continually undergo spontaneous oxidation and glycation reactions forming low levels of oxidation and glycation adduct residues. Proteolysis of oxidised and glycated proteins releases oxidised and glycated amino acids which, if they cannot be repaired, are excreted in urine.
  
  
  METHODS
  In this review we give a brief background to the classification, formation and processing of oxidised and glycated proteins in the clinical setting. We then describe the application of stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry (LC-MS/MS) for measurement of oxidative and glycation damage to proteins in clinical studies, sources of error in pre-analytic processing, corroboration with other techniques - including how this may be improved - and a systems approach to protein damage analysis for improved surety of analyte estimations.
  
  
  CONCLUSIONS
  Stable isotopic dilution analysis LC-MS/MS provides a robust reference method for measurement of protein oxidation and glycation adducts. Optimised pre-analytic processing of samples and LC-MS/MS analysis procedures are required to achieve this.
  
  
  CONCLUSIONS
  Quantitative measurement of protein oxidation and glycation adducts provides information on level of exposure to potentially damaging protein modifications, protein inactivation in ageing and disease, metabolic control, protein turnover, renal function and other aspects of body function. Reliable and clinically assessable analysis is required for translation of measurement to clinical diagnostic use. Stable isotopic dilution analysis LC-MS/MS provides a "gold standard" approach and reference methodology to which other higher throughput methods such as immunoassay and indirect methods are preferably corroborated by researchers and those commercialising diagnostic kits and reagents. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.
authors.affiliation: Clinical Sciences Research Laboratories, Warwick Medical School, University of Warwick, University Hospital, Coventry CV2 2DX, UK; Warwick Systems Biology Centre, Coventry House, University of Warwick, Coventry CV4 7AL, UK. Electronic address: P.J.Thornalley@warwick.ac.uk.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Thornalley
authors.forename: Naila
authors.initials: N
authors.lastname: Rabbani
mesh_terms: D017127:Glycation End Products, Advanced / Q000032:analysis* / Q000737:chemistry; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D010084:Oxidation-Reduction; D011506:Proteins / Q000032:analysis* / Q000737:chemistry
chemical_list: D017127:Glycation End Products, Advanced; D011506:Proteins
keywords: 3-NT; 3-nitrotyrosine; 3DG-H; 3DG-H1 (N(δ)-[5-(2,3,4-trihydroxybutyl)-5-hydro-4-imidazolon-2-yl]ornithine) and related structural isomers 3DG-H2 and 3DG-H3 see [1]; 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate; AASA; AGE; AOPP; AQC; BNX; BUL; CEL; CML; CRF; Dicarbonyl stress; ESI; FCR; FL; FN3K; FN3KRP; G-H1; GOLD; GSA; HD; LC-MS/MS; LDL; MALDI; MG; MG-H1; MOLD; MRM; MSR; Mass spectrometry; MetSO; Methylglyoxal; N(δ)-(5-hydro-4-imidazolon-2-yl)ornithine; N(δ)-(5-hydro-5-methyl-4-imidazolon-2-yl)ornithine; N(ε)-carboxymethyl-lysine; N(ε)-fructosyl-lysine; N-formylkynurenine; NFK; Nε-(1-carboxyethyl)lysine; Oxidative stress; PD; Protein glycation; Protein oxidation; SAF; TFA; UPLC; advanced glycation endproduct; advanced oxidation protein product; aminoadipic semialdehyde; bilateral nephrectomy; bilateral ureteral ligation; chronic renal failure; electrospray ionisation; fractional clearance rate; fructosamine-3-kinase; fructosamine-3-kinase related protein; glutamic semialdehyde; glyoxal-derived lysine dimer, 1,3-di(N(ε)-lysino)imidazolium salt; hemodialysis; liquid chromatography-tandem mass spectrometry; low density lipoprotein; matrix assisted laser desorption ionisation; methionine sulfoxide; methionine sulfoxide reductase; methylglyoxal; methylglyoxal-derived lysine dimer, 1,3-di(N(ε)-lysino)-4-methyl-imidazolium salt; multiple reaction monitoring; peritoneal dialysis; skin autofluorescence; trifluoroacetic acid; ultra high performance liquid chromatography