Molecular characteristics of methylglyoxal-modified bovine and human serum albumins. Comparison with glucose-derived advanced glycation endproduct-modified serum albumins.
The amino acid modification, gel filtration chromatographic, and electrophoretic characteristics of bovine and human serum albumins irreversibly modified by methylglyoxal (MG-SA) and by glucose-derived advanced glycation endproducts (AGE-SA) were investigated. Methylglyoxal selectively modified arginine residues at low concentration (1 mM); at high methylglyoxal concentration (100 mM), the extent of arginine modification increased and lysine residues were also modified. Both arginine and lysine residues were modified in AGE-SA. Analytical gel filtration HPLC of serum albumin derivatives suggested that the proportion of dimers and oligomers increased with modification in both low and highly modified MG-SA and AGE-SA derivatives relative to unmodified serum albumins. In SDS-PAGE analysis, dimers and oligomers of low-modified MG-SA were dissociated into monomers, but not in highly modified MG-SA. MG-SA had increased anodic electrophoretic mobility under nondenaturing conditions at pH 8.6, indicating an increased net negative charge, which increased with extent of modification; highly modified MG-SA and AGE-SA had similar high electrophoretic mobilities. MG-SA derivatives were fluorescent: the fluorescence was characteristic of the arginine-derived imidazolone N delta-(5-methyl-4-imidazolon-2-yl)ornithine, but other fluorophores were also present. AGE-SA had similar fluorescence, attributed, in part, to glucose-derived imidazolones. AGE formed from glucose-modified proteins and AGE-like compounds formed from methylglyoxal-modified proteins may both be signals for recognition and degradation of senescent macromolecules.
Westwood
M E
ME
Department of Chemistry and Biological Chemistry, University of Essex, Wivenhoe Park, Colchester, U.K.
Thornalley
P J
PJ
D000818:Animals; D001120:Arginine / Q000378:metabolism; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005947:Glucose / Q000737:chemistry / Q000378:metabolism*; D017127:Glycation End Products, Advanced / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000378:metabolism; D008970:Molecular Weight; D011765:Pyruvaldehyde / Q000737:chemistry / Q000378:metabolism*; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000378:metabolism*; D012967:Sodium Dodecyl Sulfate; D013050:Spectrometry, Fluorescence
D017127:Glycation End Products, Advanced; D012709:Serum Albumin; D012710:Serum Albumin, Bovine; D012967:Sodium Dodecyl Sulfate; D011765:Pyruvaldehyde; D001120:Arginine; D005947:Glucose; D008239:Lysine