Structural Identification and Molecular Interaction Modeling Analysis of Antioxidant Activity Selenium-Enriched Peptides from Selenium-Enriched Pleurotus eryngii

Abstract

This study investigated the structure-activity relationships between SePEPs (selenium-enriched peptides) and PEPs (selenium-free peptides) and compared the antioxidant activities of SePEPs and PEPs. The results showed that SePEPs exhibited higher antioxidant activity than PEPs at the same molecular weight, with the molecular weights of 0-3500 Da exhibiting the highest in vitro antioxidant activity. Chelation between selenium and peptides led to a more compact structure and increased particle density in SePEPs. A spectroscopic analysis revealed new peaks and redshifts in SePEPs, along with a higher content of hydrophobic amino acids than PEPs. A molecular interaction modeling analysis indicated that hydrogen bonding and hydrophobic interactions primarily drove the binding between selenium-containing peptides and 1,1-diphenyl-2-picrylhydrazyl (DPPH). Moreover, the solid-phase synthesized MSePGP exhibited significantly greater antioxidant activity than glutathione at high concentrations. At 10 mg/mL, the DPPH radical scavenging rate of MSePGP was 68.5 ± 2.2%. These findings provide a theoretical basis for the design and synthesis of selenium-enriched peptides with enhanced antioxidant properties.

Keywords: SePEP; antioxidant activity; molecular interaction modeling; structural identification.

Figure 1

Antioxidant activities of SePEPs and PEPs. (A): DPPH radical scavenging rate; (B): ABTS radical scavenging rate; (C): hydroxyl radical scavenging rate; (D): FRAP total antioxidant capacity (* p < 0.05).

Figure 2

TEM of SePEPs (A) and PEPs (B). The red arrows denote peptide-related particles present in the field.

Figure 3

Absorption spectra (A) UV and (B) fluorescence of SePEPs and PEPs.

Figure 4

FTIR of SePEPs and PEPs.

Figure 5

Total ion flow diagram of SePEPs (A) and secondary mass spectrum of MSePGP (B).

Figure 6

Interaction models between peptides containing selenium and DPPH ((A,B): SCSePL; (C,D): MSePGCP; (E,F): CSeSPL). Left column: 3D (the yellow regions represent the binding sites of selenium on the peptides); right column: 2D.

Figure 7

DPPH radical scavenging rates of the selenium-containing peptide (GSH = glutathione).