The role of Se in the interconversion of polymeric states of spectrin from human erythrocytes.

It has been shown that Se can markedly prevent the dissociation of spectrin from erythrocyte ghosts. We now report that the transformation of incubated spectrin oligomers to its tetramers and dimers was obviously decreased in the presence of trace amounts (0.5-2.0 p.p.m.) of Na2SeO3. The spectrin tetramers and dimers are in a reversible equilibrium and Se could alter this equilibrium in favour of tetramers. This Se effect is concentration dependent and an inverse result was obtained with higher Na2SeO3 concentrations (greater than 4.0 p.p.m.). We suggest that the equilibrium state of the spectrin tetramer-dimer may be governed by a conformation adjustment induced by Se and the difference in conformation in the presence of low and high Na2SeO3 concentration may lead to an alteration of the spectrin tetramer-dimer balance.