Identification and quantitative evaluation of the lysine-arginine crosslinks GODIC, MODIC, DODIC, and glucosepan in foods.
The presence of the various protein crosslinks GOLD 2, MOLD 3, GODIC 4, MODIC 5, DODIC 6, and glucosepan 7 in foods has been established for the first time by liquid chromatography-mass spectrometry (LC-MS) with electrospray ionization (ESI). In compounds 2 and 3 two lysine moieties, in 4-7 a lysine and an arginine side chain are joined by the crosslink. Unequivocal identification of 2-7 was achieved with independently synthesized reference material. The quantitative results for the investigated foodstuffs show MODIC 5 to be the most important Maillard crosslink. The concentrations of 5 and GODIC 4 are 5-10 fold higher than those of the corresponding imidazolium compounds 3 and 2, establishing 5 and 4 as the major food protein crosslinks derived from methylglyoxal and glyoxal, respectively. The maximum value of 151 mg MODIC 5/kg protein (equivalent to 0.42 mmol/kg protein) was found in a butter biscuit sample which also shows the highest overall Maillard crosslink content with 0.71 mmol 47/kg protein. These first quantitative results suggest that compounds 4-7 can be jointly responsible for protein polymerization in the course of food processing.
Biemel
K M
KM
Hohenheim University, Institute of Food Chemistry, Garbenstrasse 28, D-70593 Stuttgart, Germany.
Bühler
H P
HP
Reihl
O
O
Lederer
M O
MO
D001120:Arginine / Q000032:analysis / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents / Q000737:chemistry*; D005504:Food Analysis; D005511:Food Handling; D008401:Gas Chromatography-Mass Spectrometry; D006037:Glyoxal / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry; D008239:Lysine / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry*; D015416:Maillard Reaction
C403511:2-ammonio-6-((2-((4-ammonio-5-oxido-5--oxopentyl)amino)-4-methyl-4,5-dihydro-1H-imidazol-5-ylidene)amino)hexanoate; C403510:2-ammonio-6-((2-((4-ammonio-5-oxido-5-oxopentyl)amino)-4,5-dihydro-1H-imidazol-5-ylidene)amino)hexanoate; D003432:Cross-Linking Reagents; D007093:Imidazoles; D006037:Glyoxal; D001120:Arginine; D008239:Lysine