α-Glucosidase Inhibitory Effects of Defatted Egg Yolk Powder Hydrolysate and Metal Ion Chelates and Screening and Identification of Active Peptides

This research aimed to investigate the inhibitory mechanism of defatted egg yolk powder hydrolysate (DEYPH) chelated with Mg²⁺ or Ca²⁺ against α-glucosidase (α-Glu). Spectroscopic and enzyme kinetic analyses were combined to elucidate the metal ion binding characteristics and inhibition mode and liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with molecular docking was used to screen and identify key bioactive peptides. DEYPH, obtained by hydrolysis of defatted egg yolk powder (DEYP) with trypsin (2000 U/g) for 2 h, was chelated with Mg²⁺ and Ca²⁺ at a mass ratio of 4:1, pH 7, and 50 ℃, yielding DEYPH-Mg and DEYPH-Ca, respectively. After chelation with Mg²⁺ and Ca²⁺, the inhibition rate of DEYPH against α-Glu significantly increased to 76.05% and 67.05%, respectively. Spectroscopic analysis revealed that Ca²⁺ primarily bound to O and N atoms in DEYPH via non-covalent interactions, while Mg²⁺ interacted with DEYPH through non-covalent interactions and partial coordination bonds, inducing conformational changes that increased the affinity toward α-Glu. The difference in bioactivity between the two chelates was mainly attributed to variations in binding capacity and interaction modes. Enzyme kinetics studies indicated that both DEYPH and its metal chelates inhibitedα-Glu in a non-competitive manner. The key bioactive peptide YVIQEDR was identified through LC-MS/MS coupled with in silico screening. Molecular docking demonstrated that YVIQEDR binds to a non-active site of α-Glu, consistent with the enzyme kinetics results. This study provides a theoretical foundation and technical support for developing peptide-mineral complexes for use as functional food ingredients.