Selenium-chelating corn oligopeptide as a potential antioxidant supplement: investigation of the protein conformational changes and identification of the antioxidant fragment composition

摘要

A selenium-chelating corn oligopeptide (Se-COP) with high protein and low molecular weight was prepared as a selenium supplement. Weutilized infrared (IR), ultraviolet (UV), and circular dichroism (CD) spectroscopy, 1-anilinonaphthalene-8-sulfonate (ANS)-binding fluorescence spectra, and isothermal titration calorimetry (ITC) to analyze and describe Se-COP and its reactions. It was concluded that the chelation reaction was a spontaneous process driven by enthalpy and entropy, with Delta H = 3.79 x 10(4) +/- 4075 cal/mol, Delta S = 146 cal/mol, Delta G=-23356.30 +/- 126.94 cal/mol, binding constant K-a = 1.18 x 10(4) +/- 855 M-1, and binding site number n = 0.13 +/- 0.0126, and described as coordination bonds forming and hydrophobic interaction, as well as protein conformational changes including secondary and tertiary hydrophobic structure. Se-COP had strong antioxidant capacity, and mass spectrometry (MS) was used to identify the antioxidant peptide fragment, which was characterized as LLPPY and quantified at 428.95 ng/mg. This study indicated that Se-COP prepared by chelation may be a Se supplementwith antioxidant capacity that can be applied in functional foods or ingredients.