Novel post-translational modifications of human serum albumin

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. Here we report the identification of 61 novel PTMs of human serum albumin (HSA). Phosphorylation, glycosylation, nitrosylation, deamidation, methylation, acetylation, palmitoylation, geranylation, and farnesylation are examples of the identified 31 types of PTMs. Mass spectrometry was used for the identification of PTMs in a purified HSA and HSA from 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. This report adds 61 novel PTMs to the catalog of human albumin.