Hydroxyl radical production and autoxidative glycosylation. Glucose autoxidation as the cause of protein damage in the experimental glycation model of diabetes mellitus and ageing

TLDR

Glucose exposure to protein causes cleavage, conformational change, and fluorescent adduct formation, traditionally attributed to covalent glucose attachment. The study demonstrates that hydroxyl radicals from glucose autoxidation drive protein fragmentation and conformational changes, glycofluorophore formation requires metal‑catalyzed oxidative ketoaldehyde processes, and antioxidants can separate structural damage from monosaccharide incorporation, suggesting a therapeutic role.

Abstract

Protein exposed to glucose is cleaved, undergoes conformational change and develops fluorescent adducts ('glycofluorophores'). These changes are presumed to result from the covalent attachment of glucose to amino groups. We have demonstrated, however, that the fragmentation and conformational changes observed are dependent upon hydroxyl radicals produced by glucose autoxidation, or some closely related process, and that antioxidants dissociate structural damage caused by the exposure of glucose to protein from the incorporation of monosaccharide into protein. We have also provided further evidence that glycofluorophore formation is dependent upon metal-catalysed oxidative processes associated with ketoaldehyde formation. If experimental glycation is an adequate model of tissue damage occurring in diabetes mellitus, then these studies indicate a therapeutic role for antioxidants.