Methylglyoxal modification enhances the stability of hemoglobin and lowers its iron-mediated oxidation reactions: An in vitro study.
Post-translational modification of proteins by Maillard reaction, known as glycation, is thought to be the root cause of different complications, particularly in diabetes mellitus and age-related disorders. Methylglyoxal (MG), a reactive α-oxoaldehyde, increases in diabetic condition and reacts with proteins to form advanced glycation end products (AGEs) following Maillard-like reaction. In the present study, we have investigated the in vitro effect of methylglyoxal (200, 300μm) on the heme protein hemoglobin (HbA0) (100μm) after incubation for one week at 25°C. Compared to HbA0, MG-treated HbA0exhibited decreased absorbance around 280nm, reduced intrinsic fluorescence and lower surface hydrophobicity. MG treatment was not found to significantly affect the secondary structure of HbA0. The stability of MG-treated HbA0was found to be higher compared to HbA0. Moreover, H2O2-mediated iron release and subsequent iron-mediated oxidation (Fenton) reactions were found to be lower in presence of MG-treated HbA0compared to HbA0. As shown by mass spectrometric studies, MG modified Arg-92α, Arg-104β, Arg-31α and Arg-40β of HbA0to hydroimidazolone adducts. The modifications thus appear to be associated with the observed structural alterations of the heme protein. Considering the increased level of MG in diabetes mellitus as well as its high reactivity, AGEs might be associated with structural and functional modifications of the protein including physiological significance.
Department of Biophysics, Molecular Biology & Bioinformatics, University of Calcutta, 92, Acharyya Prafulla Chandra Road, Kolkata 700009, India.
Sauradipta
S
Banerjee
Department of Biophysics, Molecular Biology & Bioinformatics, University of Calcutta, 92, Acharyya Prafulla Chandra Road, Kolkata 700009, India. Electronic address: ascbmbg@caluniv.ac.in.
Abhay Sankar
AS
Chakraborti
D000595:Amino Acid Sequence; D017127:Glycation End Products, Advanced / Q000737:chemistry* / Q000378:metabolism; D006031:Glycosylation; D006441:Hemoglobin A / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology; D057927:Hydrophobic and Hydrophilic Interactions; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D015416:Maillard Reaction / Q000187:drug effects; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011499:Protein Processing, Post-Translational; D055550:Protein Stability; D017433:Protein Structure, Secondary; D011765:Pyruvaldehyde / Q000737:chemistry*; D012996:Solutions
D017127:Glycation End Products, Advanced; D012996:Solutions; C028881:hemoglobin A(0); D011765:Pyruvaldehyde; D006441:Hemoglobin A; D006861:Hydrogen Peroxide; D007501:Iron
Advanced glycation end products; Diabetes mellitus; Hemoglobin; Hydroimidazolone; Methylglyoxal; Oxidative stress