Degradation of glycated hemoglobin. Role of erythrocytic proteolytic enzymes and oxidant damage.
Glycated hemoglobin can be degraded by proteolytic enzyme(s) in the erythrocyte. The enzyme(s) co-elutes with glycated hemoglobin when the latter is separated from erythrocyte lysates using the cation-exchanger Bio Rex-70. A further purification of the Bio Rex eluant on DEAE Sephadex A-50 separated the enzyme(s) from glycated hemoglobin. Studies with the Bio Rex eluant showed that degradation of glycated hemoglobin is maximum at 37 degrees C at pH 8.6. Proteolytic degradation is inhibited by 5 mM N-ethylmaleimide (NEM), 5 mM ethylenediamine tetraacetic acid (EDTA) and 0.6 mM n-p-tosyl-L-lysine choromethyl ketone (TLCK) (100-87 and 76% inhibition respectively). This study also examines the possibility that oxidative-damage to glycated hemoglobin increases its susceptibility to proteolytic degradation. When incubated with various anti-oxidants like DTPA, uric acid, mannitol and butylated hydroxy toluene (BHT), proteolytic degradation of glycated hemoglobin decreased by 66.1, 50.7 and 38% respectively.
Raghothama
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C
Department of Biochemistry, Kasturba Medical College, Karnataka, India.
Rao
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P
D000975:Antioxidants / Q000494:pharmacology; D002411:Cation Exchange Resins; D002852:Chromatography, Ion Exchange / Q000379:methods; D003637:DEAE-Dextran / Q000031:analogs & derivatives; D003920:Diabetes Mellitus / Q000097:blood; D004912:Erythrocytes / Q000201:enzymology*; D006442:Glycated Hemoglobin / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000494:pharmacology / Q000502:physiology; D016877:Oxidants / Q000378:metabolism; D010447:Peptide Hydrolases / Q000097:blood*; D011480:Protease Inhibitors / Q000494:pharmacology; D012117:Resins, Synthetic
D000975:Antioxidants; D002411:Cation Exchange Resins; D003637:DEAE-Dextran; D006442:Glycated Hemoglobin; D007328:Insulin; D016877:Oxidants; D010447:Peptide Hydrolases; D011480:Protease Inhibitors; D012117:Resins, Synthetic; C027184:DEAE-Sephadex A-50; C026257:Bio-Rex 70