Novel Zn-Binding Peptide Isolated from Soy Protein Hydrolysates: Purification, Structure, and Digestion

Abstract

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.

Millet bran protein hydrolysates derived peptides‐zinc chelate: Structural characterization, security prediction in silico, zinc transport capacity and stability against different food processing conditions

“…These results suggested that SDDVL-zinc chelate had higher capacity to improve absorption and transportation of zinc in vivo than ZnSO 4 and zinc gluconate. Similar trend was obtained by previous studies (Sun et al, 2021;Zhu et al, 2021). The result in Figure 6f was consistent with the results in Figure 6c,e.…”

“…Results of structure–chelating activity relationship analysis of oligopeptides demonstrated that the amino group and carbonyl group adjacent to the C‐terminal or N‐terminal of peptides played a key role in formation of peptide‐Zn complexes (Lihi et al., 2017). Especially, the γ‐carboxyl group (─COOH) in Glu or Asp was an effective zinc‐binding site because it can link with zinc through ionic bond (Zhu et al., 2021). In addition, several amino acid residues with specific groups can improve zinc‐binding ability of peptides.…”

“…Based on the fragment information from the UPLC-ESI-MS/MS analysis as shown in Figure 3, a novel peptide SDDVL (547.61 Da) was identified in MBPIH-1-A. As shown in Table 1, SDDVL showed a nearly equal zincchelating capacity (43.70 mg/g) to EDTA (an excellent an effective zinc-binding site because it can link with zinc through ionic bond (Zhu et al, 2021). In addition, several amino acid residues with specific groups can improve zinc-binding ability of peptides.…”

A new iron supplement: The chelate of pig skin collagen peptide and Fe2+ can treat iron-deficiency anemia by modulating intestinal flora

“…Among these, Asp and Glu are acidic amino acids that can contribute more −COO to achieve chelation with Fe 2+ compared to neutral amino acids. These chelating abilities have been confirmed in Fe 2+ -binding peptides in whey protein hydrolysates and soy protein ( 34 , 36 ). Similarly, Arg, His, and Lys are basic amino acids that can provide −NH groups to combine with Fe 2+ ( 37 ).…”

“…The active peptides from natural sources, such as wheat, egg white, and soy, often carry trace elements with incredible functions ( 4 , 34 ). In this study, we chose pig skin as the chelating agent of Fe 2+ to obtain PSCP-Fe.…”