Binding of selenium (administered as selenite) to albumin after efflux from red blood cells

The role of albumin in the metabolism of inorganic selenium (Se) was Studied in vivo and in vitro using a HPLC-ICP-MS method. Although Se injected in the form of selenite binds selectively to albumin after being reduced to selenide and then being effluxed into the plasma, Se was shown to be metabolized normally in the absence of albumin. The reduced form of Se, selenide, bound selectively to albumin but only to a percentage of it. The thiol group and the intermolecular disulfide group at the 34th cysteinyl residue of albumin were not responsible for the selective binding of Se to albumin. Selenide was suggested to be bound to a disulfide not a thiol group, i.e., to one of the 17 disulfide bonds in a conformationally different isoform of albumin. (C) 1998 Elsevier Science B.V. All rights reserved.