Oxidized albumin. The long way of a protein of uncertain function

• Published in: Biochimica et biophysica acta Vol. 1830; no. 12; pp. 5473 - 5479
• Main Authors: Bruschi, Maurizio, Candiano, Giovanni, Santucci, Laura, Ghiggeri, Gian Marco
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2013
• Subjects: antioxidant activity; antioxidants; Antioxidants - metabolism; Focal segmental glomerulosclerosis; Humans; Models, Molecular; Nephritic syndrome; oxidants; Oxidation; Oxidation-Reduction; oxidative stress; oxygen; patients; Reactive oxygen species; Renal diseases; Serum albumin; Serum Albumin - chemistry; Serum Albumin - metabolism; sulfonic acid; sulfonic acids; thiols; LC–MS–MS; Renal diseases; Reactive oxygen species; Focal segmental glomerulosclerosis; DSC; ESI-MS; Oxidation; Serum albumin; Nephritic syndrome; HOCI; AOPPs; electrospray ionization mass spectrometry; hypochlorous acid; liquid chromatography with tandem mass spectrometry; advanced oxidation products; differential scanning calorimetry
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2013.04.017

Proteins are extremely reactive to oxidants and should represent a potential target of instable reactive oxygen. This may represent a problem for plasma proteins since they may be directly modified in vivo in a compartment where antioxidant enzymatic systems are scarcely represented. On the other hand, it is possible that some plasma components have evolved over time to guarantee protection, in which case they can be considered as anti-oxidants. To present and discuss main studies which addressed the role of albumin in plasma antioxidant activity mainly utilizing in vitro models of oxidation. To present some advances on structural features of oxidized albumin deriving from studies carried out on in vitro models as well as albumin purified in vivo from patients affected by clinical conditions characterized by oxidative stress. There are different interaction with HOCl and chloramines. In the former case, HOCl produces an extensive alteration of 238Trp and 162Tyr, 425Tyr, 47Tyr, while thiol groups are only partially involved. Chloramines are extremely reactive with the unique free SH group of albumin (34Cys) with the formation of sulfenic and sulfinic acid as intermediates and sulfonic acid as end-product. Oxidized albumin has a modified electrical charge for the addition of an acidic residue and presents α-helix and random coil reorganization with subtle changes in domain orientation. Albumin, is the major antioxidants in plasma with a concentration (0.8mM) higher than other antioxidants by an exponential factor. Functional and protective roles in the presence of oxidative stress must be defined. This article is part of a Special Issue entitled Serum Albumin. •Albumin is the main antioxidant in plasma where classical cell antioxidants are low.•In vivo oxidized albumin has a sulfonic acid residue in place of SH at 34Cys.•It also presents a modified electrical and α-helix/random coil reorganization.•HOCl produces an extensive alteration of Trp and Tyr; thiol groups are not involved.•Chloramines are extremely reactive with the unique free SH group of albumin (34Cys).