title: Length-dependent β-sheet growth mechanisms of polyalanine peptides in water and on hydrophobic surfaces.
abstract: Fibrillar assemblies by peptides are becoming one of the most promising nanomaterials due to their exceptional properties. The self-assembly of peptides into β sheets is a critical step in the fibrillization pathway. We investigated the length-dependent β-sheet growth mechanisms of polyalanine [poly(A)] peptides consisting of 6 to 24 alanines (A6 to A24) in water and on the hydrophobic surface, respectively, by molecular dynamics simulations. β-sheet growth behavior in water fits negative exponential growth model, showing that β-sheet growth rate decays exponentially with time. Meanwhile, increasing chain length leads to an accelerated decay of the β-sheet growth rate. By contrast, β-sheet growth on the surface from A6 to A18 occurs in two consecutive stages, both of which fit linear growth models. β-sheet growth rate in the first stage increases as chain length is increased, while the intermediate length peptide A12 has the highest β-sheet growth rate in the second stage. β-sheet growth behavior of A24 on the surface still fits negative exponential model. Overall, the hydrophobic surface accelerates β-sheet growth by enhancing local concentration and reducing conformational entropy of poly(A) peptide, and the β-sheet growth of the intermediate length peptide A12 is the fastest on the surface. Our simulation results shed light on understanding the accelerated peptide fibrillization on the hydrophobic surface.
authors.affiliation: College of Materials Science and Engineering, South China University of Technology, Guangzhou Guangdong, 510641, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Mu
authors.affiliation: College of Materials Science and Engineering, South China University of Technology, Guangzhou Guangdong, 510641, China.
authors.forename: Binqing
authors.initials: B
authors.lastname: Tang
authors.affiliation: College of Materials Science and Engineering, South China University of Technology, Guangzhou Guangdong, 510641, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D003198:Computer Simulation; D019281:Dimerization; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D008958:Models, Molecular; D008970:Molecular Weight; D046912:Multiprotein Complexes / Q000737:chemistry / Q000648:ultrastructure; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D046912:Multiprotein Complexes; D010455:Peptides; D014867:Water; C019529:polyalanine