Conformation Studies of Copolypeptides Composed of γ-Methyl-D-glutamate and γ-Methyl-L-glutamate
1973; Springer Nature; Volume: 4; Issue: 1 Linguagem: Inglês
10.1295/polymj.4.10
ISSN1349-0540
AutoresAkio Nakajima, Toshio Hayashi, Kohzo Itoh, Takashi Fujiwara,
Tópico(s)Advanced Polymer Synthesis and Characterization
ResumoCopolypeptides composed of γ-methyl-D-glutamate and γ-methyl-L-glutamate covering the whole range of copolymer compositions were synthesized by the NCA method using triethylamine(TEA) as the initiator. The X-ray diffraction measurements for these D, L-copoly(γ-methyl glutamate)s in solid state indicated that these copolypeptide molecucles can exist in a conformation very similar to that of the α-helix of PMLG or PMDG. Infrared absorption spectra of solid films were also measured. The sum of right- and left-handed helix contents was determined from intensities of amide V bands. Optical rotatory dispersions of these copolymers in helicogenic solvents were used to ascertain their helical character. The parameter b0 of Moffitt—Yangs equation for D, L-copoly(γ-methyl glutamate) in helicogenic solvent could give the difference between right- and left-handed helix content. Thus the right-handed helix, left-handed helix, and random coil contents were estimated separately. In order to test the relative stability of helices of these copolypeptides, the optical rotatory dispersions were examined in DCA—DCE mixtures as functions of solvent composition.
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