Département de chimie moléculaire

Availability and high reactivity of $\alpha$-oxoaldehydes have been approved by exptl. techniques not only in vivo systems but also in foodstuffs. In this article we re-examine the mechanism of glucosepane formation by using computational model chem. D. functional theory has been applied to propose a new mechanism for glucosepane formation through reaction of $\alpha$-oxoaldehydes with Me amine (MA) and Me guanidine (MGU) models of lysine and arginine residues resp. This non enzymic process can be described in three main steps: (1) Schiff base formation from Me amine, Me glyoxal (MGO) (2) addn. of Me guanidine and (3) addn. of glyceraldehyde. We show that this process is thermodynamically possible and presents a rate-detg. step with a reasonable free energy barrier equal to 37.8 kcal mol-1 in water solvent. Comparisons were done with the mechanism formation of GODIC (glyoxal-derived imidazolium cross-link) and MODIC (Me glyoxal-derived imidazolium cross-link), two other important cross-links in vivo. [on SciFinder(R)]