In this study, a novel Zn-binding peptide, Lys−Tyr−Lys−Arg−Gln−Arg−Trp (KYKRQRW), was purified and identified from soy protein isolate hydrolysates (SPIHs). The Zn-binding peptide exhibited improved Zn-binding capacity (83.21 ± 2.65%) than SPIH solutions. CD, NMR, and Fourier transform infrared spectroscopy were used to confirm the complexation between Zn and the peptide. The results showed that the Zn-binding peptide formed a folding structure with part of the β-sheet (29.3−13.4%) turning into random coils (41.7−57.6%) during complexation. It was further proved that the binding sites were located at the oxygen atoms on the carboxyl group of the Trp side chain and nitrogen atoms on the amino group of the Lys side chain. Moreover, the Zn−peptide complex exhibited increased solubility than ZnSO 4 during simulated gastrointestinal digestion. This study highlighted that the novel soy peptide possessed a strong zinc chelate rate and had a positive effect on the gastrointestinal stability of Zn which could be utilized as a functional ingredient in future.

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Summary Selenium (Se) is an essential trace element in human health. In this article, egg white polypeptide (EWP) was used as the reducing agent and stabiliser to prepare a novel type of EWP‐selenium complex nanoparticles (EWP‐SeNPs). Particle size, morphology, FT‐IR, stability, and functional properties of EWP‐SeNPs were characterised. The results showed that EWP‐SeNPs were 30–50 nm in diameter and were spherical. The SeNPs complexed with the EWP through O‐ and N‐ containing groups. This reaction was entropy‐driven spontaneous and the binding force was mainly hydrophobic. The stability of EWP‐SeNPs was best at pH = 10. Moreover, EWP‐SeNPs showed significantly inhibitory effect on HepG‐2 cells in the range of 6.2500 to 50.0000 μg mL−1. Anti‐bacterial effect occurred when the concentration of EWP‐SeNPs was 1.2500 mg mL−1. This study would provide a green method for synthesising stable SeNPs, which was helpful for further evaluation in the food field.

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