Ammonium Sulfate Precipitation but Not Delipidation is a Valuable Method for Human Albumin Preparation for Biological Studies

Background: Glycated hemoglobin level is considered as one of the main clinical parameters used for diabetes diagnosis. With a shorter half-life than hemoglobin, glycated human serum albumin appears to be an alternative and relevant marker for glycemic control and for the diagnosis of numerous associateddiabetes complications. The characterization of albumin as an alternative marker in clinical studies required its delipidation after the protein purification from plasma. The aim of this study was to find a reliable and convenient method for albumin delipidation and purification which does not have significant impact on the redox state, intrinsic structural and functional integrities of human serum albumin. Methods: Affinity chromatography and ammonium sulfate precipitation were the two different techniques used for albumin isolation from plasma and delipidation was performed with ethanol-ether mixture. The biochemical (redox state), structural and functional (antioxidant, affinity and esterase properties) integrities of purified HSA were determined by using biochemical assays and fluorescence spectroscopy measurements. Results: The two-step precipitation of HSA with ammonium sulfate enabled to purify albumin exhibiting preserved structural and functional properties in terms of antioxidant and enzymatic activity and through a rapid and efficient protocol. By contrast, batch- or chromatography affinity-mediated purification presented more backwards than ammonium sulfate precipitation method. In addition, our results showed the delipidation step following the purification should not to be considered as it impacted both structure and function of albumin. Conclusion: Such novel insights may in turn unlock novel protocol developments that should help reach a better understanding of modified albumin involvement in insulin resistance progression.