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Updated: Jan 8, 2026

Quantifying the Binding Interactions Between CuII and Peptide Residues in the Presence and Absence of Chromophores
Published on: April 5, 2022
Unraveling the differential mechanism of casein phosphopeptide- quercetin covalent/non-covalent complexes: structural
Danjun Guo1, Siying Wei1, Mingfei Song1
1College of Food Science & Engineering, Wuhan Polytechnic University, Wuhan 430023, PR China; Hubei Key Laboratory for Processing and Transformation of Agricultural Products (Wuhan Polytechnic University), Wuhan 430023, PR China.
Abstract:
The structural differences and differential binding mechanism of casein phosphopeptide-quercetin (CPP-QR) covalent/non-covalent complexes were characterized by using multispectral analysis, isothermal titration calorimetry (ITC) and molecular dynamics (MD) simulation. Both bindings induced fluorescence quenching, with covalent binding causing more pronounced CPP conformational changes. Covalent/non-covalent complexes reduced CPP surface hydrophobicity by 30.86 % and 6.2 % respectively. Covalent interaction significantly decreased α-helix and β-turn, increased random coil (P < 0.05); non-covalent interaction reduced α-helix, enhanced β-sheet, β-turn and random coil (P < 0.05). Microstructurally, CPP was spherical/plate-like, covalent complex smaller plate-like, non-covalent complex honeycomb-like. ITC showed QR-CPP binding ratios of 2.29 (covalent) and 1.13 (non-covalent). MD revealed covalent bonds dominated covalent complex, hydrogen bonds/hydrophobic interactions dominated non-covalent one, with covalent complex having lower binding free energy, RMSD and RMSF. The study aimed to reveal differential effects of interactions on CPP structure and complex formation mechanism.
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