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Small-Angle X-ray Scattering Study of Protein Complexes with Tea Polyphenols.
Ce Shi1, Haifeng Tang1,2, Jie Xiao3
1Key Laboratory of Synthetic Rubber & Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry , Changchun 130022, People's Republic of China.
Journal of Agricultural and Food Chemistry
|January 5, 2017
Summary
Tea polyphenols like EGCG and catechin promote protein aggregation by bridging bovine serum albumin (BSA) and trypsin. EGCG is more potent, forming denser aggregates than catechin, with BSA showing greater stability.
Area of Science:
- Biophysics
- Biochemistry
- Materials Science
Background:
- Understanding protein complex structure and aggregation is key to elucidating bioactivities.
- Ligand binding significantly influences protein conformation and aggregation behavior.
Purpose of the Study:
- To investigate the structural changes and aggregation of bovine serum albumin (BSA) and trypsin upon binding with tea polyphenols (catechin and EGCG).
- To quantify the effect of polyphenol-to-protein ratio on complex and aggregate formation.
- To compare the aggregation-promoting capabilities of EGCG and catechin and analyze the resulting aggregate structures.
Main Methods:
- Solution small-angle X-ray scattering (SAXS) to determine complex and aggregate structures.
- Fluorescence spectroscopy to ascertain binding affinity and the number of bound polyphenols.
Main Results:
- Tea polyphenols act as bridging agents, promoting protein and protein complex aggregation.
- EGCG demonstrated a stronger ability to induce complex formation and aggregation compared to catechin.
- Aggregates induced by EGCG had denser cores and smoother surfaces, while catechin-induced aggregates were loosely packed with rough surfaces.
- Bovine serum albumin (BSA) exhibited higher conformational stability during complex formation than trypsin.
- Trypsin's synergistic unfolding led to larger aggregates in the presence of higher polyphenol concentrations.
Conclusions:
- Tea polyphenols effectively modulate protein complex formation and aggregation.
- The structural characteristics of the aggregates are dependent on the type of polyphenol and protein.
- Findings provide insights for preparing protein complex-based particles and understanding polyphenol-protein interactions.
