Micellization of surfactin and its effect on the aggregate conformation of amyloid beta(1-40).
The aggregation of amyloid beta-peptide (Abeta(1-40)) into fibrils is a key pathological process associated with Alzheimer's disease. This work has investigated the micellization process of biosurfactant surfactin and its effect on the aggregation behavior of Abeta(1-40). The results show that surfactin has strong self-assembly ability to form micelles and the micelles tend to form larger aggregates. Surfactin adopts a beta-turn conformation at low micelle concentration but a beta-sheet conformation at high micelle concentration. The effect of surfactin on the Abeta(1-40) aggregation behavior exhibits a strong concentration-dependent fashion. Below the critical micelle concentration of surfactin, the electrostatic binding of surfactin monomers on Abeta(1-40) causes Abeta(1-40) molecules to unfold. Assisted by the hydrophobic interaction among surfactin monomers on the Abeta(1-40) chain, the conformation of Abeta(1-40) transfers to the beta-sheet structure, which promotes the formation of fibrils. At low surfactin micelle concentration, besides the electrostatic force and hydrophobic interaction, hydrogen bonds formed between surfactin micelles and adjacent Abeta(1-40) peptide chains may promote the ordered organization of these Abeta(1-40) peptide chains, thus leading to the formation of beta-sheets and fibrils to a great extent. At high surfactin micelle concentration, the separating of Abeta(1-40) chains by the excessive surfactin micelles and the aggregation of the complexes of Abeta(1-40) with surfactin micelles inhibit the formation of beta-sheets and fibrils.
Han
Yuchun
Y
Key Laboratory of Colloid and Interface Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Huang
Xu
X
Cao
Meiwen
M
Wang
Yilin
Y
D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000378:metabolism; D002151:Calorimetry / Q000379:methods; D002942:Circular Dichroism; D006860:Hydrogen Bonding; D055666:Lipopeptides / Q000737:chemistry* / Q000378:metabolism; D008823:Micelles; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010456:Peptides, Cyclic / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D055672:Static Electricity
D016229:Amyloid beta-Peptides; D055666:Lipopeptides; D008823:Micelles; D010446:Peptide Fragments; D010456:Peptides, Cyclic; C078592:amyloid beta-protein (1-40); C009365:surfactin peptide