LAUSR

AIM Identify novel post-translational modifications in human serum albumin. BACKGROUND Serum albumin is the most abundant protein in plasma, has many physiological functions, and is in contact with most of the cells and tissues of the human body. Post-translational modifications (PTMs) may affect functions, stability, and localization of albumin. OBJECTIVE Identify novel PTMs in human serum albumin by mass spectrometry. METHODS Human serum albumin (HSA) was used for tryptic digestion in-solution or in-gel. Mass spectrometry was applied to identify PTMs in HSA. 3-dimensional modeling was applied to explore potential impact of PTMs on known functions of albumin. RESULTS Here we report the identification of 61 novel PTMs of human serum albumin. Phosphorylation, glycosylation, nitrosylation, deamidation, methylation, acetylation, palmitoylation, geranylation, and farnesylation are examples of the identified PTMs. Mass spectrometry was used for the identification of PTMs in a purified HSA and HSA from the human plasma. Three-dimensional modeling of albumin with selected PTMs showed the location of these PTMs in the regions involved in interactions of the albumin with drugs, metals, and fatty acids. The location of PTMs in these regions may modify the binding capacity of albumin. CONCLUSION This report adds 61 novel PTMs to the catalog of human albumin.