PROTEIN-BOUND SELENIUM IN THE SEEDS OF COCO-DE-MONO (LECYTHIS-OLLARIA)

High selenium concentrations (7-12 g/kg dry mass) were found in the se eds of the selenium-accumulator plant coco de mono (Lecythis ollaria). In order to obtain information on the protein-bound part of selenium in extracts of these seeds, dialysis and sodium dodecyl sulfate-polyac rylamide gel electrophoresis (SDS-PAGE) were used combined with neutro n activation analysis. Extractions were carried out at pH 4.5 and 7.5. In both cases about 90 % of the element was dissolved. Of the extract ed selenium only 9 % was shown to be firmly bound to proteins at pH 4. 5 and 29 % at pH 7.5. For the protein-bound selenium, concentrations o f 0.7 g and 2.4 g per kg of seeds and 40 and 25 g per kg of extractabl e protein were determined at pH 4.5 and 7.5, respectively. By analyzin g the protein fractions separated by SDS-PAGE the element was found to be present in extremely selenium-rich proteins with molecular masses below 20 kDa.