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


Biochim Biophys Acta. 2013 Apr 22;


Authors: Bruschi M, Candiano G, Santucci L, Ghiggeri GM


Abstract

BACKGROUND: 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. SCOPE OF REVIEW: 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 oxidised albumin deriving from studies carried out on in vitro models as well albumin purified in vivo from patients affected by clinical conditions characterized by oxidative stress. MAJOR CONCLUSIONS: There are different interaction with HOCl and chloramines. In the former case, HOCl produces an extensive alteration of (238)Trp and (162)Tyr, (425)Tyr, (47)Tyr, while thiol groups are only partially involved. Chloramines are extremely reactive with the unique free SH group of albumin ((34)Cys) with formation of sulfenic and sulfinic acid as intermediates and sulfonic acid as end-product. Oxidised albumin has a modified electrical charge for addition of an acidic residue and presents α-helix and random coil reorganization with subtle changes in domain orientation. GENERAL SIGNIFICANCE: Albumin, is the major antioxidants in plasma with a concentration (0.8 mM) higher than other antioxidants by an exponential factor. Functional and protective roles in presence of oxidative stress must be defined.

PMID: 23618696 [PubMed - as supplied by publisher]