Detection and determination of selenoproteins by nuclear techniques

Microbeam X-ray spectrometry, energy-dispersive X-ray fluorescence analysis, and neutron activation analysis were evaluated for the detection of selenium contained in the selenoprotein glutathione peroxidase. The glutathione peroxidase had been previously separated using polyacrylamide gel electrophoresis. The use of Bragg-reflected polarized X-ray beams was employed in the X-ray fluorescence measurements to minimize the problem of scatter owing to the gel matrix. Current detection limits of selenium in a gel matrix are 2.1 ng in the bench-top microbeam X-ray system and 30–60 ng using XRF with polarized beams. Neutron activation analysis was used for qualitycontrol measurements, with a detection limit here of <0.08 ng. The work has in principle established the feasibility of such an approach.     

Evidence for erythrocyte membrane glycoproteins being carriers of blood-group P1 determinants

The contribution of different membrane constituents to the bloodgroup P₁ activity of human erythrocytes was investigated. Pronase digestion of native red cell stroma or partition between butanol and water had no serologically detectable effect, whereas pronase-treatment of previously butanol-extracted membranes liberated virtually all blood-group P₁ determinants from the ghosts. On Laemmli gels, all P₁ activity was found in the band 4.5 region. Thus it is concluded that, in addition to the well-documented P₁ glycolipid, also membrane glycoproteins are carriers of blood-group P₁ determinants.