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Effect of different glycation agents on Cu(II) binding to human serum albumin, studied by liquid chromatography, nitrogen microwave-plasma atomic-emission spectrometry, inductively-coupled-plasma mass spectrometry, and high-resolution molecular-mass spectrometry
- Corrales Escobosa, Alma Rosa, Wrobel, Katarzyna, Yanez Barrientos, Eunice, Jaramillo Ortiz, Sarahi, Ramirez Segovia, Alejandra Sarahi, Wrobel, Kazimierz
- Analytical and bioanalytical chemistry 2015 v.407 no.4 pp. 1149-1157
- binding sites, copper, gel chromatography, glucose, glycation, homeostasis, human serum albumin, nitrogen, quantitative analysis, reversed-phase liquid chromatography, tandem mass spectrometry
- The ability of human serum albumin to capture unbound copper under different clinical conditions is an important variable potentially affecting homeostasis of this element. Here, we propose a simple procedure based on size-exclusion chromatography with on-line UV and nitrogen microwave-plasma atomic-emission spectrometry (MP-AES) for quantitative evaluation of Cu(II) binding to HSA upon its glycation in vitro. The Cu-to-protein molar ratio for non-glycated albumin was 0.98 ± 0.09; for HSA modified with glyoxal (GO), methylglyoxal (MGO), oxoacetic acid (GA), and glucose (Glc), the ratios were 1.30 ± 0.22, 0.72 ± 0.14, 0.50 ± 0.06, and 0.95 ± 0.12, respectively. The results were confirmed by using ICP-MS as an alternative detection system. A reduced ability of glycated protein to coordinate Cu(II) was associated with alteration of the N-terminal metal-binding site during incubation with MGO and GA. In contrast, glycation with GO seemed to generate new binding sites as a result of tertiary structural changes in HSA. Capillary reversed-phase liquid chromatography with electrospray-ionization quadrupole-time-of-flight tandem mass spectrometry enabled detection and identification of Cu(II) coordinated to the N-terminal metal-binding site (Cu(II)–DAHK) in all tryptic digests analyzed. This is the first report confirming Cu(II)–DAHK species in HSA by means of high-resolution tandem mass spectrometry, and the first report on the use of MP-AES in combination with chromatographic separation.