ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
It has already been show that the helix senses of poly(β-benzyl L-aspartate) and poly(β-methyl L-aspartate) are left-handed, while the poly esters of n-propyl, isopropyl, n-butyl, and phenethyl L-asparate are all right-handed. The effect of changes in helix sense from the left-handed to the right-handed α-helical form on the infrared spectra of copolymers of benzyl L-aspartate with ethyl, n-butyl, isopropyl, n-propyl, and phenethyl L-aspartate have been studied. Those show that for the right-handed helical form the amide band frequencies fall within the range given by Elliott,7 while for the left-handed form the frequencies are higher. The frequency ranges for the two helix senses are given and have been used to show that poly (β-n-propyl L-aspartate) in chloroform solution undergoes a transition from the right-handed to the left-handed helix form on heating. Polarized infrared studies of the different copolymers show that the disposition of the side chain ester groups is different for the two forms. Although methyl L-aspartate forms a left-handed α-helix similar to benzyl L-aspartate, the introduction of methyl L-aspartate residues into poly (β-benzyl L-aspartate) prevents the formation of the ω-helix. The factors involved in the formation of this helix form are discussed.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1968.360060702
