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Synthesis and conformational study of poly(0,0′‐dicarbobenzoxy‐ L ‐β‐3,4‐dihydroxyphenyl‐α‐alanine)
Author(s) -
Yamamoto Hiroyuki,
Hayakawa Tadao
Publication year - 1977
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1977.360160717
Subject(s) - dichloroacetic acid , trifluoroacetic acid , chemistry , chloroform , helix (gastropod) , alanine , random coil , solvent , polymer chemistry , optical rotation , stereochemistry , organic chemistry , amino acid , circular dichroism , ecology , biochemistry , snail , biology
High‐molecular‐weight poly(0,0′‐dicarbobenzoxy‐ L ‐β‐3,4‐dihydroxyphenyl‐α‐alanine) was prepared by the N ‐carboxyanhydride method. From the results obtained by a study of the optical rotation, nuclear magnetic resonance, and solution infrared absorption, the conformation of poly(0,0′‐dicarbobenzoxy‐ L ‐β‐3,4‐dihydroxyphenyl‐α‐alanine) depended greatly on the solvent taking a right‐handed helix with [θ] 225 = −13,600 ∼ −18,900 in alkyl halides, a left‐handed helix with [θ] 228 = 22,100 ∼ 24,800 in cyclic ethers or trimethylphosphate, and a random coil structure in dichloroacetic acid, trifluoroacetic acid, or hexafluoroacetone sesquihydrate. The polypeptide underwent a right‐handed helix‐coil transition in chloroform/dichloroacetic acid (or trifluoroacetic acid) mixed solvents and a left‐handed helix‐coil transition in dioxane/dichloroacetic acid (or trifluoroacetic acid) mixed solvents. The results were compared with those of poly(0‐carbobenzoxy‐ L ‐tyrosine).