TY - JOUR
TI - Well-Defined Homopolypeptides, Copolypeptides, and Hybrids of Poly(l-proline)
AU - Manos Gkikas
AU - Hermis Iatrou
AU - Nikolaos S. Thomaidis
AU - Paschalis Alexandridis
AU - Nikos Hadjichristidis
JO - Biomacromolecules
PY - 2011
VL - 12
TODO - 6
SP - 2396--2406
PB - American Chemical Society (ACS)
SN - 1525-7797, 1526-4602
TODO - 10.1021/bm200495n
TODO - Amine groups;  Amino group;  Compositional homogeneity;  Copolypeptides;  Ethylene oxides;  Free amino acids;  FTIR;  High purity;  L-proline;  Low purity;  N-carboxy anhydrides;  Purification method;  Synthesized polymers, Carboxylic acids;  Ethylene;  Hydrogen;  Monomers;  Polyethylene oxides;  Polymers, Amino acids, amine;  amino acid;  copolypeptide;  homopolypeptide;  hydrogen;  monomer;  n carboxy anhydride;  poly(boc lysine)beta poly(proline);  poly(ethylene oxide)beta poly(proline);  poly(gamma benzyl glutamate)beta poly(proline);  poly(proline) beta poly(ethylene oxide) beta poly(proline);  polymer;  polypeptide;  polyproline;  unclassified drug, amino acid sequence;  article;  hybrid;  infrared spectroscopy;  mass spectrometry;  nuclear magnetic resonance;  priority journal;  protein purification;  synthesis, Anhydrides;  Biocompatible Materials;  Circular Dichroism;  Drug Carriers;  Lysine;  Magnetic Resonance Spectroscopy;  Mass Spectrometry;  Molecular Conformation;  Peptides;  Polyethylene Glycols;  Proline;  Spectroscopy, Fourier Transform Infrared;  Temperature
TODO - l-Proline is the only, out of 20 essential, amino acid that contains a cyclized substituted α-amino group (is formally an imino acid), which restricts its conformational shape. The synthesis of well-defined homo- and copolymers of l-proline has been plagued either by the low purity of the monomer or the inability of most initiating species to polymerize the corresponding N-carboxy anhydride (NCA) because they require a hydrogen on the 3-N position of the five-member ring of the NCA, which is missing. Herein, highly pure l-proline NCA was synthesized by using the Boc-protected, rather than the free amino acid. The protection of the amine group as well as the efficient purification method utilized resulted in the synthesis of highly pure l-proline NCA. The high purity of the monomer and the use of an amino initiator, which does not require the presence of the 3-N hydrogen, led for the first time to well-defined poly(l-proline) (PLP) homopolymers, poly(ethylene oxide)-b-poly(l-proline), and poly(l-proline)-b-poly(ethylene oxide)-b-poly(l-proline) hybrids, along with poly(γ-benzyl-l-glutamate)-b- poly(l-proline) and poly(Boc-l-lysine)-b-poly(l-proline) copolypeptides. The combined characterization (NMR, FTIR, and MS) that results for the l-proline NCA revealed its high purity. In addition, all synthesized polymers exhibit high molecular and compositional homogeneity. © 2011 American Chemical Society.
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