The α‐CH proton chemical shift in the coil conformation of poly( L ‐alanine)
1977; Wiley; Volume: 178; Issue: 5 Linguagem: Inglês
10.1002/macp.1977.021780525
ISSN0025-116X
AutoresTetsuo Asakura, Isao Ando, Atsuo Nishioka,
Tópico(s)Molecular Sensors and Ion Detection
ResumoAbstract In order to clarify the cause of the change of the α‐CH proton chemical shift through the helix‐coil transition of poly( L ‐alanine), the α‐CH chemical shift in a coil form was calculated by taking into account the intramolecular shielding effect and compared with the value in a helical form. The coil α‐CH peak was predicted to resonate upfield by about 0,1 ppm from the helical peak in contrast to the downfield shift observed in experiments. Thus it was suggested that the observed low field shift in trifluoroacetic acid (TFA) mainly comes from the solvent effect by TFA including the rearrangement of the charge distribution along the poly(L‐alanine) chain.
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