Isolation of selenium organic species from antarctic krill after enzymatic hydrolysis

Abstract

Total selenium content and the selenium distribution in the soluble and insoluble protein-bound fractions obtained after aqueous extraction and centrifugation of Antarctic krill samples were determined. About 26% of the total selenium ( Se) (2.4 μg/g dry weight) was found in the supernatant and the rest was in the pellet. The digestion of the protein and the isolation of low molecular selenium-containing fractions was achieved by enzymatic hydrolysis followed by size-exclusion chromatography in conjunction with graphite furnace atomic absorption spectrometry. From the applied various proteinases (trypsin, -chymotrypsin, subtilisin, pronase E), the treatment with pronase E led to best recovery of the total Se. About 96% of the total selenium was found in the hydrolysate, mainly in low molecular weight fractions. 15% of the low molecular weight Se-species were in fractions with molecular weights in the range of amino acids.