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Role of reactive oxygen species on the formation of the novel diagnostic marker ischaemia modified albumin
  1. D Roy1,*,
  2. J Quiles1,
  3. D C Gaze2,
  4. P Collinson2,
  5. J C Kaski1,
  6. G F Baxter3
  1. 1Cardiological Sciences, St George’s Hospital Medical School, London, UK
  2. 2Chemical Pathology, St George’s Hospital Medical School
  3. 3Department of Basic Sciences, The Royal Veterinary College, London UK
  1. Correspondence to:
    Dr Gary F Baxter
    Department of Basic Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 OUT, UK; gfbaxter{at}

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Ischaemia modified albumin (IMA) is a recently developed biomarker of transient myocardial ischaemia.1 Circulating IMA is increased in patients with myocardial ischaemia, after percutaneous coronary intervention,2,3 or in acute coronary syndromes.4 The test has recently been licensed by the US Food and Drug Administration for diagnostic use in suspected myocardial ischaemia. IMA is serum albumin in which the N-terminus has been chemically modified. The diagnostic albumin Co2+ binding (ACB) test is based for IMA on the observation that the affinity of serum albumin for Co2+ is reduced after N-terminus modifications. It has been proposed that reactive oxygen species (ROS) such as superoxide (O2) and hydroxyl (OH) radicals generated during myocardial ischaemia–reperfusion modify the N-terminus of serum albumin resulting in IMA formation but, so far, direct evidence to support this is scarce. We hypothesised that ROS generation causes the formation of IMA. Our objective was to model the formation of IMA in vitro by using chemically generated ROS and the OH radical scavenger mercaptopropionylglycine (MPG).


All reagents were obtained from Sigma-Aldrich (Poole, Dorset, UK) and normal human serum from the North London Transfusion Service (London, UK). Serum pH was 7.35–7.45 at 37°C and was unaltered by any of the reactants during the 15 minute experimental time course. Five millilitre serum aliquots (eight replicate experiments per group) were randomly selected for the following incubations for 15 minutes at 37°C. Group 1, peroxide treated (H2O2): serum was incubated with H2O2 100 μM. Group 2, superoxide treated (O2): serum was incubated with a xanthine-xanthine oxidase O2 generating system consisting of 100 μM xanthine plus 0.05 U/ml xanthine …

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  • * Also the Department of Basic Sciences, The Royal Veterinary College, London UK