Identification of zinc-binding peptides in ADAM17-inhibiting whey protein hydrolysates using IMAC-Zn2+ coupled with shotgun peptidomics

M Chinonye Udechukwu,Chibuike C Udenigwe,Chi Dang

doi:10.1186/s43014-020-00048-4

M Chinonye Udechukwu, Chibuike C Udenigwe + Show 1 more

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https://doi.org/10.1186/s43014-020-00048-4

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Abstract

Food components possessing zinc ligands can be used to inhibit zinc-dependent enzymes. In this study, zinc-binding peptides were derived from whey protein hydrolysates, and their ultrafiltration (> 1 and < 1 kDa) fractions, produced with Esperase (WPH-Esp), Everlase and Savinase. Immobilized metal affinity chromatography (IMAC-Zn2+) increased the zinc-binding capacity of the peptide fraction (83%) when compared to WPH-Esp (23%) and its < 1 kDa fraction (40%). The increased zinc-binding capacity of the sample increased the inhibitory activity against the zinc-dependent “a disintegrin and metalloproteinase 17”. LC-MS/MS analysis using a shotgun peptidomics approach resulted in the identification of 24 peptides originating from bovine β-lactoglobulin, α-lactalbumin, serum albumin, β-casein, κ-casein, osteopontin-k, and folate receptor-α in the fraction. The identified peptides contained different combinations of the strong zinc-binding group of residues, His+Cys, Asp+Glu and Phe+Tyr, although Cys residues were absent in the sequences. In silico predictions showed that the IMAC-Zn2+ peptides were non-toxins. However, the peptides possessed poor drug-like and pharmacokinetic properties; this was possibly due to their long chain lengths (5–19 residues). Taken together, this work provided an array of food peptide-based zinc ligands for further investigation of structure-function relationships and development of nutraceuticals against inflammatory and other zinc-related diseases.Graphical abstract

Highlights

Food proteins are rich sources of peptides with an inherent capacity to bind divalent metals, such as zinc (Sun et al 2020)
Whey protein hydrolysates demonstrated zinc-binding capacity The classic method of producing bioactive peptides involves enzymatic hydrolysis of food proteins, which can be selected based on knowledge of the presence of bioactive peptides within their primary structures (Udenigwe and Aluko 2012)
The release of peptides during hydrolysis with Esperase, Everlase and Savinase is demonstrated by the higher content of free amino nitrogen of the resulting WPH (~ 200 Serine mequiv NH2/g protein) compared to the parent whey protein isolate (WPI) (65 Serine mequiv NH2/g protein) (Udechukwu et al 2018)

Summary

Introduction

Food proteins are rich sources of peptides with an inherent capacity to bind divalent metals, such as zinc (Sun et al 2020). Tyr, whose functional side chains act as nucleophilic ligands to form coordinate complexes with zinc (Bischoff and Schlüter 2012; Udechukwu et al 2016; Walters et al 2018; Sun et al 2020). Such zinc-binding peptides could have useful nutritional applications as dietary zinc carriers to enhance zinc bioaccessibility and bioavailability (Walters et al 2018; Udechukwu et al 2016, 2018). Zinc-binding Cys-containing tripeptides derived from rye secalin inhibited the in vitro

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