Polypeptide?PEG Conjugates via Ring Opening Polymerization of <scp>l</scp> ?Alanine <i>N</i> ?Carboxyanhydride

The synthesis of well-defined homo- and co-polypeptides L-alanine (L-Ala) by ring-opening polymerization (ROP) its N-carboxyanhydride (NCAs), either via suspension/interfacial- or solution phase-polymerization using 10-undecene-1-amine ?,?-diamino poly(ethylene glycol) (8 1.5 kDa) as primary amine initiators is reported. When conducting ROP NCA-alanine under suspension/interfacial conditions, back-biting can be preferably eliminated to reach enhanced control the polymerization. Well-defined structures resulting homo-polypeptides with chain lengths ranging from n = 9 31 amphiphilic polyalanine conjugates molecular weights 3.8 15.3 kDa a degree 18 102 are obtained. Structural characterization performed 1H-NMR, gel permeation chromatography (GPC) in hexafluoroisopropanol (HFIP), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Subsequently, folding triblock variety parameters such temperature, length, backbone composition further transitions these secondary investigated HFIP HFIP-H2O mixtures circular dichroism (CD) spectroscopy. A solvent induced helical switch 310-helix ?-helix when changing HFIP–water observed, water inducing helicity stronger both, homo-polyalanine poly(alanine)-PEG-poly(alanine) copolymers.