ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A block copolymer [γ-Et-DL-Glu]m [L-Trp]n was prepared using N-carboxy anhydrides (NCA) of L-tryptohan and γ-ethyl DL-glutamate. The block copolymer, dissolved in trifluoroethanol (TFE)-dichloroacetic acid (DCA) mixtures, exhibited a sharp change in the specific rotation at 546 mμ when the solvent composition reached 70-75% DCA content. Optical rotatory dispersion (ORD) and circular dichroism (CD) measurement were carried out in TFE solution in the spectral range 180-350 mμ. Indole side-chain chromophores were found to be optically active in the polymer. On the other hand, these groups exhibit very small optical activity in the model compound C6H3—CH2—O—CO—(L-Trp)2—O—CH3. Indole groups therefore appear to be in a dissymmetric environment only in the polymer. From these data it was concluded that poly-L-Trp is in some type of helical conformation in TFE. Strong overlapping of CD bands from side-chain chromophores and peptides chromophores in the wavelength range 185-240 mμ does not allow definite conclusions to be drawn about the type of helical conformation which exists in poly-L-Trp in TFE solution.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1968.360060707
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