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Complexing of basic pancreatic proteinase inhibitor with soybean phospholipid multilamellar vesicles
O P Tiourina1, T V Sharf, A A Selishcheva
1School of Chemistry, Lomonosov Moscow State University, Moscow, 119899, Russia.
Abstract:
The formation of complexes of basic pancreatic proteinase inhibitor (BPTI) with multilamellar vesicles (MLV) from six preparations of soybean phospholipids of various composition was studied. When BPTI, a non-membrane protein, interacts with MLV, the vesicles aggregate, forming a precipitate of protein-lipid complexes. The BPTI content in the protein-lipid complexes increases with decreasing pH of the medium and on addition of negatively charged components into the lipid mixture. The protein-induced aggregation of the phospholipid vesicles is suggested to be mainly determined by electrostatic forces. The antiproteinase activity of BPTI in the complexes was rather low but increased up to 70% of the initial activity on addition of an ionic detergent (sodium deoxycholate).
Insights
Basic pancreatic proteinase inhibitor (BPTI) forms complexes with soybean phospholipid vesicles, causing aggregation. This protein-lipid complex formation is influenced by pH and lipid charge, primarily driven by electrostatic forces.
Area of Science:
- Biochemistry
- Biophysics
- Materials Science
Background:
- Basic pancreatic proteinase inhibitor (BPTI) is a non-membrane protein.
- Multilamellar vesicles (MLV) are composed of soybean phospholipids.
- Understanding protein-lipid interactions is crucial in biological and material sciences.
Purpose of the Study:
- To investigate the complex formation between BPTI and MLV.
- To determine factors influencing BPTI-MLV complex formation and stability.
- To assess the antiproteinase activity of BPTI within these complexes.
Main Methods:
- Studied complex formation using six soybean phospholipid preparations of varying compositions.
- Analyzed BPTI-MLV interactions under different pH conditions.
- Investigated the effect of negatively charged lipid components on complexation.
- Assessed antiproteinase activity of BPTI in complexes with and without ionic detergents.
Main Results:
- BPTI interacts with MLV, leading to vesicle aggregation and protein-lipid complex precipitate.
- BPTI content in complexes increases with decreasing pH and addition of negative charges.
- Protein-induced vesicle aggregation is primarily mediated by electrostatic forces.
- BPTI retained low antiproteinase activity in complexes, but activity increased up to 70% with sodium deoxycholate.
Conclusions:
- Electrostatic interactions are the main drivers of BPTI-induced MLV aggregation.
- Lipid composition and environmental pH significantly affect BPTI-phospholipid complex formation.
- BPTI's antiproteinase function can be modulated within protein-lipid complexes, with potential for recovery using detergents.