N-Terminal pyrazinones: a new class of peptide-bound advanced glycation end-products.
The reaction of peptide Gly-Ala-Phe with the alpha-dicarbonyl compounds glyoxal and methylglyoxal was studied under physiological conditions (pH=7.4, 37 degrees C). Using HPLC with UV and fluorescence detection, a rapid derivatization of the peptide and the concomitant formation of well-defined products were observed. The products, which showed characteristic UV absorbance (lambda(max)=320 to 340 nm) and fluorescence (lambda(ex)=330 to 340 nm, lambda(em)=395 to 405 nm), were identified by ESI-MS and NMR spectroscopic analysis as the N-terminally pyrazinone-modified peptides I (N-[2-(2-oxo-2H-pyrazin-1-yl)-propyl]-phenylalanine) and II (N-[2-(5-methyl-2-oxo-2H-pyrazin-1-yl)-propionyl]-phenylalanine). Model experiments revealed that the reactivity of the N-termini of peptides towards a derivatization by glyoxal is in the same order of magnitude as that of arginine, which generally is attributed as main target for alpha-dicarbonyl compounds in proteins. Incubation of insulin with glyoxal proved the protein-bound formation of pyrazinones, with the N-terminus of the B-chain as the main target. According to these results, we conclude that N-terminal pyrazinones represent a new type of advanced glycation end-products (AGEs) with significance for biological systems and foods.
Krause
R
R
Institute of Food Chemistry, Technical University of Dresden, Dresden, Germany.
Kühn
J
J
Penndorf
I
I
Knoll
K
K
Henle
T
T
D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004220:Disulfides / Q000737:chemistry; D017127:Glycation End Products, Advanced / Q000737:chemistry*; D006037:Glyoxal / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008956:Models, Chemical; D010455:Peptides / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011719:Pyrazines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013053:Spectrophotometry; D013696:Temperature; D013997:Time Factors; D014466:Ultraviolet Rays
D004220:Disulfides; D017127:Glycation End Products, Advanced; D006454:Hemoglobins; D007328:Insulin; D010455:Peptides; D011719:Pyrazines; D006037:Glyoxal