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13C and 1H NMR studies of helix-coil transition of poly(β-benzyl-L-aspartate) and poly(γ-benzyl-L-glutamate): Behavior in nonprotonating solvent mixtures, and origin of solvent-induced chemical shift

✍ Scribed by Yasuyuki Suzuki; Yoshio Inoue; Riichirô Chûjô

Publisher
Wiley (John Wiley & Sons)
Year
1977
Tongue
English
Weight
574 KB
Volume
16
Category
Article
ISSN
0006-3525

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✦ Synopsis

Abstract

From the results of ^13^C‐nmr measurement of poly(β‐benzyl‐L‐aspartate) and its model compounds in dimethyl sulphoxide/deuterated chloroform mixtures, it was found that the side chain of poly(β‐benzyl‐L‐aspartate) is solvated by dimethyl sulphoxide in the region more than dimethyl sulphoxide 20% (v/v), where the backbone maintains the α‐helix. The chemical shift differences in the benzyl group carbons of poly(γ‐benzyl‐L‐glutamate) (trifluoroacetic acid/deuterated chloroform) accompanied by the helix‐coil transition, originate from the interaction between the ester group of the side chain and trifluoroacetic acid. The chemical shift difference in the ester carbon is similar. On the other hand, the chemical shift differences of the side‐chain carbons in the alkyl portion (C^β^, C^γ^) originate not only from the interaction between the ester group of the side chain and trifluoroacetic acid, but also from some other unknown factors. The chemical shift differences of the side‐chain carbons of poly(β‐benzyl‐L‐aspartate) originate from the interaction between the ester group of the side chain and trifluoroacetic acid.

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