Rat plasma selenoprotein P properties and purification.
A selenoprotein in rat plasma, selenoprotein P, was fractionated and characterized. Plasma collected from rats 3 h post injection of 75SeO3(2-) contained one 75Se-labeled protein, selenoprotein P. Selenoprotein P was fractionated using salt precipitation, Affi-Gel Blue, and DEAE chromatography. The 75Se-containing subunit of selenoprotein P was purified to 90% homogeneity using SDS-polyacrylamide gel electrophoresis followed by electroelution. This isolation resulted in an 850-fold purification of the 75Se-containing subunit of selenoprotein P with a 15% yield of 75Se radioactivity. The molecular weight of selenoprotein P in plasma was 98,000. The 75Se-containing subunit of selenoprotein P had a molecular mass of 57 kDa as determined by SDS-polyacrylamide gel electrophoresis. Isoelectric focusing under nondenaturing conditions resulted in a band of 75Se radioactivity at pH 5.4. A comparison of Coomassie Blue- and silver-staining properties of selenoprotein P in SDS-polyacrylamide gels was made. Reverse-phase HPLC and Sephadex G-50 chromatography of tryptic peptides of the 57 kDa subunit of selenoprotein P yielded several peaks of 75Se radioactivity. These results indicate that 75Se is present in several locations within the 57 kDa subunit of selenoprotein P.
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Department of Food Science and Technology, University of California, Davis 95616.
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D000818:Animals; D001345:Autoradiography; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D008297:Male; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification; D011506:Proteins / Q000032:analysis* / Q000302:isolation & purification; D051381:Rats; D011919:Rats, Inbred Strains; D012643:Selenium / Q000097:blood* / Q000302:isolation & purification; D012644:Selenium Radioisotopes; D051149:Selenoprotein P; D051140:Selenoproteins; D014357:Trypsin
D010446:Peptide Fragments; D011506:Proteins; D012644:Selenium Radioisotopes; D051149:Selenoprotein P; D051140:Selenoproteins; D014357:Trypsin; D012643:Selenium