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Figure 1 Production of collagen crosslinks. Glucose interacts with collagen to form a Schiff base. This reaction occurs fast and is reversible. The collagen Schiff base can then rearrange over a period of days to generate an Amadori product (i.e., glycated collagen). This step occurs faster in the forward than in the reverse direction and, thus, glycated collagen accumulates. Glycated collagen can undergo further chemical modification to yield complex compounds and crosslinks known as advanced glycosylation end-products (AGEs). Collagen AGEs are known to be more stable, virtually irreversible, and more resistant to proteolysis.