Structure and composition of a potential antioxidant obtained from the chelation of pea oligopeptide and sodium selenite

Abstract

A selenium-chelating pea oligopeptide (Se-POP) was prepared from pea oligopeptide (POP) and sodium selenite (SS) via chelation. Se-POP is rich in organic selenium as 57.23% ± 0.36%. The chelation reaction was spontaneous and endothermic, with a binding constant Ka = 2.64 × 104 ± 1.60 × 103 M−1 and binding site number n = 0.27 ± 0.01. Spectral analysis indicated protein conformational changes consistent with chelation, that the peptide chain to fold and curl, causing random coil and β-turn decreasing and the peptide side-chain radicals folding and burying. The antioxidant capacity of Se-POP was increased relative to that of POP. One novel antioxidant peptide fragment was obtained from Se-POP and identified as PPKIYP, presenting at a concentration of 29.47 ng/mg. The results indicated that Se-POP might be a new organic Se supplement with antioxidant capacity, which may be easily absorbed due to its low molecular weight.

Keywords

• Pea
• Low-molecular-weight peptides
• Chelation
• Conformation changes
• Antioxidant activity
• Peptide fragment quantification