ABSTRACT: This study aims to analyze and compare the post-translational modification differences between human plasma- and genetic recombination-derived human serum albumin (HSA) in clinical treatments in China. 6 different post-translational modifications, including acetylation, succinylation, crotonylation, phosphorylation, beta-hydroxybutyrylation, and lactylation, were detected using pan-specific antibodies through Western blot. The samples, consisting of human plasma-derived HSA (pHSA) from six different manufacturers and recombinant HSA (rHSA) expressed in yeast and oryza sativa, underwent detection of types of post-translational modifications. 4D label-free PTMs quantitative proteomic analysis was conducted to detect N-glycosylation and the above-mentioned post-translational modifications in pHSA and rHSA samples, and analyze the differences in modification sites and levels. Through Western blot analysis, all six pHSA and two rHSA samples were positive in the band of albumin (66.5 kDa) for the six post-translational modifications. Further analysis using 4D label-free PTMs quantitative proteomics revealed 25 (29) acetylated, 30 (32) succinylated, 41 (50) malonylated, 15 (23) phosphorylated, 36 (30) beta-hydroxybutyrylated, and 27 (34) lactylated modification sites in pHSA and rHSA samples and no N-glycosylation modification sites. The analysis results identified 1 acetylation (ALB_K160), 2 beta-hydroxybutyrylation (ALB_K569, ALB_K426), 3 crotonylation (ALB_K264, ALB_K581, ALB_K560), and 15 phosphorylation specific modification sites in pHSA, as well as 3 crotonylation (ALB_K560, ALB_K562, ALB_K75), 1 succinylation (ALB_K490), and 23 phosphorylation specific modification sites in rHSA. In pHSA (rHSA), 2 (6) acetylation, 10 (12) succinylation, 0 (9) crotonylation, 1 (9) phosphorylation, 6 (0) beta-hydroxybutyrylation, and 0 (7) lactylation specific modification sites were found. Additionally, in the common modification sites of pHSA and rHSA, pHSA showed up-regulation of amberylation (16:1) and beta-hydroxybutyrylation (12:2) in more sites, and up-regulation of acetylation (7:11), crotonylation (2:11), phosphorylation (1:8), and lactylation (1:14) in less sites compared to rHSA. In clinical treatment, the used pHSA and rHSA in China generally exhibit acetylation, succinylation, crotonylation, phosphorylation, beta-hydroxybutyrylation, and lactylation, and there are differences in the site characteristics and modification levels of these modifications between pHSA and rHSA. Further experimental investigations are needed to explore the impact of post-translational modification differences on the biological function, efficacy, and safety of pHSA and rHSA.
Xinmei Cao 
