Reversible Helix Sense Inversion in Surface-Grafted Poly(β-phenethyl-l-aspartate) Films

Abstract

The reversible manipulation of the helix screw sense in surface-grafted poly(β-phenethyl-L-aspartate) (PPELA) films by means of external stimuli was investigated. Ringopening polymerization of β-phenethyl-L-aspartate N-carboxyanhydride initiated from primary amino-functionalized silicon and quartz substrates results in surfacegrafted PPELA films in which the end-grafted polypeptide chains have a right-handed R-helical conformation. Upon annealing of the film at 150 °C for 30 min, a helix screw sense inversion takes place and the grafted chains adopt a left-handed π-helical conformation. In the solid state, this left-handed π-helical form is completely stable and cannot be changed by reheating and/or cooling. Upon immersion of the annealed grafted film in chloroform or other helicogenic solvents, the grafted polypeptide chains completely revert to their original right-handed R-helical form. Successive annealing and solvent treatment steps show that this helix sense inversion cycle can be repeated many times.

Handedness preference and switching of peptide helices. Part I: Helices based on protein amino acids

“…In connection to this, in 1958–1960, the groups headed by Blout and Bradbury were the first to report that the polydisperse homo‐polymer poly‐[ l ‐Asp(OBzl)] n , where OBzl is benzyloxy, represents an exception to the general rule because it exists as a left‐handed helix in solutions of halogenated hydrocarbons (CHCl 3 , CH 2 Cl 2 ), as shown principally by optical rotatory dispersion (ORD) measurements. Subsequently, this area of research was greatly expanded by Goodman and coworkers , including one of the authors of the present review article (C. T.), for strictly monodisperse l ‐Asp β ‐ester oligopeptides, and by Hashimoto et al , again Bradbury et al , Malcolm , Scheraga et al , Abe et al , and other groups , for polydisperse polypeptides. In their last papers, the Hashimoto and Goodman groups used the much more advanced and unambiguous chirospectroscopic technique circular dichroism (CD) in the far‐UV region to characterize the screw sense of the helical structure of the l ‐Asp β ‐ester peptides.…”

Polyaspartates as Thermoresponsive Enantiodifferentiating Helically Chiral Alignment Media for Anisotropic NMR Spectroscopy

“…The synthesis of PPLA is already described in literature, but not for its enantiomer PPDA. Since a successful synthesis route for PBLG has been established in our group, we followed this protocol for both enantiomers of poly‐β‐phenethylaspartate (PPA).…”

Synthesis of P4VP-b-PBLG Diblock Copolymers and Their Self-Assembly Behavior

“…P4VP-alkyne homopolymers were prepared by atom transfer radical polymerization (ATRP) [15]. Briefly, in an oven-dried Schlenk tube, 4VP monomer (24.0 mmol, 2.52 g), CuCl (0.240 mmol, 24.0 mg), PMDETA (0.240 mmol, 55.2 X. S. Huang et al Journal of Materials Science and Chemical Engineering mg) and α-propyl chloropropionate (0.240 mmol, 35.0 mg) were dissolved in 2 ml isopropyl alcohol under nitrogen protection.…”