Purification of the newly found selenium-containing proteins in the arterial wall and brain of the rat

Previously several selenium-containing proteins with different subunit mole cular masses (M-r) were detected in the arterial wall and brain of rats. In continuation of this work, after labeling of rats In vivo with [Se-75]sele nite, the new selenium-containing proteins of interest were purified on a S ephadex G-200 column followed by preparative isoelectric focusing. Nuclear analytical methods (gamma-counter and gamma-detector) were applied in the d etection and identification of the Se-75-labeled proteins. The two Se-75-co ntaining proteins from the arterial wall migrated as 15.0- and 67.0-kDa spe cies on SDS-PAGE gels with pI values of 4.5 and 5.1, respectively. The thre e Se-75-containing proteins from brain purified to homogeneity had M-r valu es of 18.0, 30.0, and 42.9 kDa and pI values of 6.3, 6.5, and 6.0, respecti vely. Of these proteins, the 67.0-, 42.9-, and 30.0-kDa species may be yet not characterized selenoproteins with important biological functions. (C) 2 000 Academic Press.