Synthèse et structure de la poly‐<i>O</i>‐carbobenzoxy <scp>L</scp>‐ tyrosine et de copolymères de <i>O</i>‐carbobenzoxy <scp>L</scp>‐tyrosine et de glutamate de benzyle ou d'aspartate de benzyle

Abstract

Abstract The optical rotatory dispersion of copolymers of O ‐carbobenzoxy‐ L ‐tyrosine and benzyl L (or D )‐glutamate as well as benzyl L ‐aspartate, dissolved in nonpolar solvent, has been studied. Moffitt's equation permits the determination of b 0 coefficients whose variation, with varying composition in amino acid residues, suggests that the molecules of poly‐ O ‐carbobenzoxy‐ L ‐tyrosine have a helical structure similar to that of poly‐(benzyl L ‐glutamate). Results obtained from infrared spectroscopy and x‐ray diffraction show that the copolymers possess a helical conformation in the solid state, even when they are very rich in carbobenzoxy‐ L ‐tyrosine residues. The value of the b 0 , coefficient for poly‐ O ‐carbobenzoxy‐ L ‐tyrosine may be explained by a regular stacking of the chromophore groups around the helical backbone. The ordering of the molecules of this polymer in a purely helical structure seems favored by the insertion of a small number of foreign residues in the polypeptide chain.