Favored and disfavored pathways of protein crosslinking by glucose: glucose lysine dimer (GLUCOLD) and crossline versus glucosepane.
We describe the isolation and molecular characterization of a novel glucose-lysine dimer crosslink 1,3-bis-(5-amino-5-carboxypentyl)-4-(1',2',3',4'-tetrahydroxybutyl)-3H-imidazolium salt, named GLUCOLD. GLUCOLD was easily formed from the Amadori product (fructose-lysine). However, when BSA was incubated with 100 mM glucose for 25 days, the levels of the lysine-lysine glucose crosslinks GLUCOLD and CROSSLINE were only 21 and <1 pmol/mg, respectively, compared to 611 pmol/mg protein for the lysine-arginine GLUCOSEPANE crosslink, in spite of more than 20 potential lysine-lysine crosslinking sites in the protein. Mechanistic investigation revealed that metal-free phosphate ions catalyzed formation of fructose-lysine and all three crosslinks from amino acids, while cationic MOPS buffer had an opposite effect. This together with the rapid formation of N (6)-1,4-dideoxy-5,6-dioxoglucosone derivatives by dicarbonyl trapping agents, such as 1,2-diaminobenzene or γ-guanidinobutyric acid, strongly suggests that enolization of the Amadori product and trapping of the 5,6-dioxo derivative by arginine residues constitutes the major pathway for glucose-mediated crosslinking in proteins.
Nemet
Ina
I
Departments of Pathology and Biochemistry, Case Western Reserve University, Wolstein Research Bldg., 2103 Cornell Road, Cleveland, OH 44106-7288, USA.
Strauch
Christopher M
CM
Monnier
Vincent M
VM
D003432:Cross-Linking Reagents / Q000737:chemistry; D005947:Glucose / Q000737:chemistry*; D017127:Glycation End Products, Advanced / Q000737:chemistry*; D008239:Lysine / Q000737:chemistry*; D015416:Maillard Reaction; D011506:Proteins / Q000737:chemistry*
D003432:Cross-Linking Reagents; D017127:Glycation End Products, Advanced; D011506:Proteins; C543060:glucosepane; D005947:Glucose; D008239:Lysine