Spectroscopic Studies of the Effects of Glycation of Human Serum Albumin on L-Trp Binding

Abstract

Modification of proteins by nonenzymatic glycation is one of the underlying factors that contribute to the development of the complications of diabetes. Human serum albumin (HSA) is one of the major targets of interaction with glucose through the Maillard reaction. The effects of 1 and 5 mg/ml glucose concentrations, which are consistent with blood glucose levels found in diabetic patients, on human serum albumin were studied by circular dichroism and fluorescence spectroscopy in sodium phosphate buffer, pH 7.4. Partial denaturation and changes in the structural integrity of HSA are caused by glycation at lower (1 mg/ml) and higher (5 mg/ml) concentrations of glucose. To study the relationship between structure and function, we investigated the interaction of L-tryptophan (L-Trp) with glycated and non-glycated HSA. The results showed that L-Trp, as the only free amino acid that substantially binds to HSA, has a lower affinity for the glycated form (especially at low concentrations of glucose) than for non-glycated HSA.

Human serum albumin: From bench to bedside

“…HSA glycation in patients affected by diabetes mellitus impairs both ligand binding and anti-oxidant properties (Bourdon et al, 1999;Sakata et al, 2002;Cohen, 2003;Van Campenhout et al, 2006;Barzegar et al, 2007;Faure et al, 2008a). Notably, the Cu(II) binding capacity of glycated HSA is lower than that of the non-glycated protein (Sakata et al, 2002).…”

“…Moreover, the Fe(III)-binding anti-oxidant capacity of HSA is markedly reduced in diabetes mellitus patients (Van Campenhout et al, 2006). Lastly, binding and transport of Trp by glycated HSA is reduced (Barzegar et al, 2007).…”

“…In particular, HSA glycation in patients affected by diabetes mellitus (Cohen, 2003) impairs both ligand binding and antioxidant properties (Bourdon et al, 1999;Sakata et al, 2002;Van Campenhout et al, 2006;Barzegar et al, 2007;Faure et al, 2008a). Since the Cu(II) binding capacity of glycated HSA is lower than that of the non-glycated protein (Sakata et al, 2002), glycated HSA exacerbates Cu(II)-induced LDL oxidation, probably by the generation of superoxide (Bourdon et al, 1999;Sakata et al, 2002).…”

Alginate as an antiglycating agent for human serum albumin

“…We previously studied the structural and thermodynamic properties of glycated HSA in the presence of glucose after 7 days of incubation [25,26] using fluorescence and circular dichroism techniques, in addition to measuring the tryptophanbinding of glycated HSA in the presence of glucose [27]. Although glucose is major metabolic sugar, in the glycation reaction pathway some AGEs (e.g.…”

Emerging trends in optical sensing of glycemic markers for diabetes monitoring

“…Most of the literature reports focus on the application of fluorescence spectroscopy for characterization of glycated albumin [41] and for studying the effects of glycation on changes in binding and oxidation properties of albumin [42]. For example, fundamental studies measuring the fluorescence lifetimes of native and glycated albumin proteins (human serum albumin and bovine serum albumin) have revealed that the shorter lifetime (when the decay curve is fitted by double and triple exponential functions) is sensitive to the onset and the progression of glycation [43].…”