title: Induction of Secondary Structure through Micellization of an Oppositely Charged Pair of Homochiral Block- and Homopolypeptides in an Aqueous Medium.
abstract: Polyion complex (PIC) formation is an attractive method for obtaining molecular assemblies owing to their facile fabrication process in aqueous media, but more insights are required in order to control the higher-dimensional structures of polypeptide-based PICs. Herein, the PIC formation behavior of oppositely charged homochiral polypeptides, poly-L-lysine and poly(ethylene glycol)-b-poly(L-glutamate) (PEG-PLG), and their secondary structures are carefully studied in water. PIC formation takes place in a polymer concentration-dependent manner, and clear β-sheet formation is observed at polymer concentrations ≥0.3 mg mL(-1). The results also confirm that multimolecular aggregation is a prerequisite for β-sheet formation, which indicates that the inner hydrophobic environment of PICs is favorable for β-sheet formation. Furthermore, the PEG weight fraction, stereoregularity of the polypeptide, and ionic strength of the solutions are found to be key factors for generating a secondary structure, presumably because these factors can contribute to the tuning of the inner environment of PICs. This method of producing water-soluble nanoassemblies from oppositely charged polypeptides may expedite self-assembly studies in biological systems and be incorporated into various molecular systems to exploit protein-mimicking features.
authors: Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors: Omer F
authors: OF
authors: Mutaf
authors: Faculty of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka, 819-0395, Japan.|Center for Molecular Systems, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka, 819-0395, Japan.
authors: Akihiro
authors: A
authors: Kishimura
authors: Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors: Yuki
authors: Y
authors: Mochida
authors: Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors: Ahram
authors: A
authors: Kim
authors: Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.|Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors: Kazunori
authors: K
authors: Kataoka
mesh_terms: D002236:Carbohydrate Conformation; D057927:Hydrophobic and Hydrophilic Interactions; D008823:Micelles; D015394:Molecular Structure; D009994:Osmolar Concentration; D010455:Peptides / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011099:Polyglutamic Acid / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*; D012996:Solutions; D055672:Static Electricity; D014867:Water / Q000737:chemistry
chemical_list: D008823:Micelles; D010455:Peptides; D012996:Solutions; D014867:Water; D011107:Polylysine; D011099:Polyglutamic Acid; D011092:Polyethylene Glycols
keywords: block copolymers; polyion complexes; polypeptides; secondary structure; stereoregularity