ISSN:
0887-624X
Keywords:
poly(L-Aze-L-Pro)
;
poly[(L-Pro)3-L-Aze]
;
synthesis conformation
;
CD
;
MR
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The synthesis, characterization, and conformational assessment of poLy(L-Aze-L-Pro) and poly[(L-Pro)3-L-Aze] are reported. The polymers were prepared by using the pentachlorophenol active ester as the polymerizable tetrapeptide derivatives. The copolymer, poly(L-Aze-L-Pro), assumes a Form II helix in polar solvents, and is converted into a form I-like helix at a critical solvent composition of ethanol to trifluoroethanol. The CD spectrum of this Form I-like conformation of poly(L-Aze-L-Pro) is similar to that of poly(trans-5-isopropyl-L-proline), indicating that the rigid four-membered ring at the alternating position can lock in the structure by a mechanism similar to that of a bulky substituent at the trans-5-position of proline. The helix conformation of this copolymer was unfolded in a 0.2M CaCl2 aqueous solution. In contrast to poly(L-Aze-L-Pro), the copolymer of poly[(L-Pro)3-L-Aze] contains both cis and trans peptide bond geometry when dissolved in a 90:10 ETOH-H2O mixture. The conversion of the mixed conformation of poly[(L-Pro)3-L-Aze)] into a polyproline Form II-like structure occurred in highly polar solvent environments such as water.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pola.1992.080300405
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