Structural and Functional Insights into S-thiolation of Human Serum Albumins

Nakashima F, et al., 8(1):932, Sci Rep., 2018

Human serum albumin (HSA) is the most abundant protein in human blood plasma. HSA plays a key role in the maintenance of redox balance in the extracellular fluids. It has a reactive free sulfhydryl group at Cys34, which can undergo oxidation. Therefore, HSA can exist both in reduced and oxidized forms. However, the molecular and functional details of oxidized HSAs remain unclear. Described herein are the structural and functional insights into S-thiolation of human serum albumins by analyzing serum proteins from normal and hyperlipidemic individuals. Homocysteine/homocystine binding to rHSA was studied by Bio-Layer Interferometry (BLI) using a Pall ForteBio Octet RED instrument equipped with Super Streptavidin (SSA) Biosensor probes. Biotinylated rHSA was immobilized onto SSA Biosensor tips. Subsequently, biotinylated rHSA loaded sensor tips were immersed in wells containing rHAS samples. Overall results of this study suggest that the S-thiolation takes place not only at Cys34 but also at multiple other cysteine residues in the disulfide bonds of HSA, offering new insights into structural alternation of HSA via S-thiolation.

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