Semi-synthetic human albumin isoforms: Production, structure, binding capacities and influence on a routine laboratory test.

Human Serum Albumin (HSA) undergoes Post-Translational-Modifications (PTMs) leading to isoforms affecting its oncotic and non-oncotic properties. HSA is comprised of several isoforms whose abundance may vary with pathologies such as diabetes, kidney and liver diseases. Studying their impact separately may help to understand their sources and potential pathogenicity and further their evaluation as biomarkers. The present study examined semi-synthetic HSA isoforms to investigate independently their structure by means of advanced mass spectrometry techniques (LC-TOF-MS and ICP-MS), influence on the HSA binding/antioxidant activities using a binding capacity test, and potential impact on albumin quantification by a routine immunoturbidimetric assay. Applying different chemical reactions to a commercial HSA solution, we obtained different solutions enriched up to 53 % of native HSA, 78 % of acetylated HSA, 71 % of cysteinylated HSA, 94 % of oxidized HSA, 58 % of nitrosylated HSA and 96 % of glycated HSA, respectively. Moreover, the semi-synthetic isoforms showed differently altered binding capacities for a panel of ligands (Cu, Cd, Au, Ds and L-T4). Furthermore, immunoturbidimetry was found to be insensitive to the presence and abundance of the different isoforms. The fully characterized semi synthetic HSA isoforms obtained should be useful to further investigate their pathogenicity and potential roles as biomarkers.