MODIFICATION OF LIGAND LOAD AND STRUCTURE OF HUMAN SERUM-ALBUMIN ISOLATED BY VARIOUS METHODS

The effect of various isolation procedures on the physicochemical char acteristics of human serum albumin (HSA) was studied by differential s canning calorimetry and infrared spectroscopy. Albumin was isolated fr om healthy donors by fractionation of blood plasma with polyethylene g lycol (PEG) and subsequent ion-exchange chromatography; its melting th ermograms were similar to thermograms of the protein in unfractionated blood plasma. Endotherms of HSA isolated by affinity chromatography ( AC) and preparative electrophoresis (E) were bimodal, whereas PEG-HSA melted as a single phase, These differences may be due to increased co ntents of non-esterified fatty acids in AC-HSA samples and modificatio n of the secondary protein structure in E-HSA samples, In patients wit h uremia, chronic hepatitis, and peritonitis the thermograms of HSA me lting indicate that the PEG method better preserves the thermodynamic characteristics of the various pathological HSAs. The data demonstrate the advantage of the PEG method for isolation of native HSA preparati ons under normal or pathological conditions.