Abstract
Poly(S-2-benzyloxycarbonylaminoethyl-L-cysteine), poly(S-3-benzyloxycarbonylaminopropyl-L-cysteine), poly(S-L-2-benzyloxycarbonylaminopropyl-L-cysteine), and poly(S-D-2-benzyloxycarbonylaminopropyl-L-cysteine) were prepared by the N-carboxyanhydride method. The protected polymers were converted into poly(S-2-aminoethyl-L-cysteine), poly(S-3-aminopropyl-L-cysteine), poly(S-L-2-aminopropyl-L-cysteine), and poly(S-D-2-aminopropyl-L-cysteine) through decarbobenzoxylation with hydrogen bromide. The conformation of the above polypeptides was studied by means of their infrared (IR) spectra, X-ray diffractions, optical rotatory dispersions (ORD), and circular dichroisms (CD). By means of the IR spectra and X-ray diffractions, the polymers are found to be in the β-conformation in the solid state. The results of the ORD and the CD suggest that the β—coil transition of these protected polymers occurs at 3—15-% DCA in a chloroform—DCA mixture. In the pH range 3.0—8.0 in an aqueous solution, the deprotected polymers are in a random coil structure. However, when the pH is increased to about 9, these polymers change into the β-conformation. The results of IR measurements of these polypeptides in D2O also indicated that they had the β-conformation.
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Hayakawa, T., Kondo, Y. & Murakami, Y. Syntheses and Conformational Studies of Poly(S-aminoalkyl-L-cysteines) and Their Benzyloxycarbonyl Derivatives. Polym J 6, 424–430 (1974). https://doi.org/10.1295/polymj.6.424
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DOI: https://doi.org/10.1295/polymj.6.424