Argpyrimidine (ARP) is an advanced glycation end product thought to be generated from a reaction between methylglyoxal and arginine residues in proteins. In this study, we observed marked accumulation of an approximately 56 kD protein, reactive to anti-ARP antibodies, in the red blood cells (RBCs) of some patients with refractory schizophrenia. This ARP-modified protein was purified from the blood of schizophrenic patients and identified as selenium binding protein 1 (SBP1) by LC-MS/MS. This is the first report of ARP-modified proteins accumulating in RBCs of patients with diseases involving carbonyl stress. We also observed high accumulation of ARP-modified SBP1 in the RBCs of patients with chronic kidney disease. Therefore, this modified protein may be a novel marker of carbonyl stress.
Keywords: Argpyrimidine; Biomarker; Carbonyl stress; Red blood cell; Schizophrenia; Selenium binding protein 1.
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