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Interaction-induced structural transformation of lysozyme and kappa-carrageenan in binary complexes
O N Makshakova1, L R Bogdanova1, D A Faizullin2
1Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky Str., 420111, Kazan, Russia; Sirius University of Science and Technology, 1 Olympic Ave, 354340, Sochi, Russia.
Interactions between kappa-carrageenan and lysozyme form complexes with distinct structures. Unordered kappa-carrageenan induces beta-structures in lysozyme, potentially preventing protein aggregation.
Area of Science:
- Biochemistry
- Materials Science
- Protein Chemistry
Background:
- Carrageenans are sulfated polysaccharides used in food and pharmaceuticals.
- Lysozyme is an enzyme with antimicrobial properties.
- Protein-polysaccharide interactions are crucial for understanding biomaterial properties and biological processes.
Purpose of the Study:
- To investigate the structural and conformational changes of kappa-carrageenan and hen egg-white lysozyme upon complex formation.
- To elucidate the binding patterns and molecular interactions between kappa-carrageenan and lysozyme under different conditions.
- To explore the potential applications of these interactions in preventing protein aggregation.
Main Methods:
- Formation and characterization of kappa-carrageenan/lysozyme complexes in dilute and concentrated solutions.
- Fourier Transform Infrared (FTIR) spectroscopy to analyze secondary structures of protein and polysaccharide.
- Molecular modeling to visualize and understand binding interactions at the molecular level.
Main Results:
- In dilute solutions, insoluble complexes (kappa-carrageenan/lysozyme ratio 0.3) formed, where kappa-carrageenan remained unordered and induced beta-structure in lysozyme.
- In concentrated mixtures, complexes (21 disaccharide units/protein mole) showed helical kappa-carrageenan and native-like lysozyme structure.
- Molecular modeling revealed distinct binding preferences: helical carrageenan favored positive charges in lysozyme's alpha-domain, while unordered carrageenan interacted with the beta-domain, stabilizing beta-structures.
Conclusions:
- The conformation of kappa-carrageenan dictates its interaction mode and influence on lysozyme structure.
- Unordered kappa-carrageenan preferentially binds to beta-structure-rich regions of proteins.
- These findings support the development of carrageenan-based strategies for protecting proteins against amyloid-like aggregation.
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