Syntheses and conformational studies of poly(s-aminoalkyl-homocysteine)s and their benzyloxycarbonyl derivatives

Tadao Hayakawa, Yoshiyuki Kondo, Nagao Kobayashi

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4 Citations (Scopus)

Abstract

Poly(S-2-benzyloxycarbonylaminoethyl-L-homocysteine), poly(S-3-benzyl-oxycarbonylaminopropyl-L-homocysteine), poly(S-L-2-benzyloxycarbonylaminopropyl-L-homocysteine), and poly(S-L-2-benzyloxycarbonylaminopropyl-D-homocysteine) were prepared by the NCA method. The protected polymers were converted into poly(S-2-amino-ethyl-L-homocysteine), poly(S-3-aminopropyl-L-homocysteine), pol(S-L-2-aminopropyl-L-homocysteine), and poly(S-L-2-aminopropyl-D-homocysteine) through decarbobenzoxylation with hydrogen bromide. The conformation of these polypeptides was studied by means of their infrared(IR) spectra, optical rotatory dispersions(ORD), and circular dichroisms(CD). From the IR measurements all polymers were found to be in the α-helix in the solid state. The results of the ORD and CD suggest that these protected polymers take an α-helix conformation in chloroform and a random coil conformation in DCA. In a chloroform—DCA mixture, the helix—coil transition of these polymers was observed at 60—80—% DCA. The ORD and CD curves ofthe deprotected polymers showed that the polymers took a random coil in the pH range below 7. However, when the pH is increased above 7, the spectra gradually change into the α-helix. Moreover, thehelix—coil transition of the polypeptide occurs at a lower pH range when methanol is added to its aqueous solution.

Original languageEnglish
Pages (from-to)538-543
Number of pages6
JournalPolymer Journal
Volume7
Issue number5
DOIs
Publication statusPublished - 1975 Sep

Keywords

  • Circular dichroism
  • Infrared spectra
  • Optical rotatory dispersion
  • Poly (s-benzyloxy car bony laminoalkyl-homocysteine)s
  • Poly(s'-aminoalkyl-homocysteine)s
  • Synthesis
  • ɑ-helix–coil transition

ASJC Scopus subject areas

  • Polymers and Plastics
  • Materials Chemistry

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