ISSN:
0006-3525
Keywords:
poly(β-phenethyl L-asparate
;
right-handed α-helix
;
left-handed α-helix
;
1,1,2,2-tetrachloroethane
;
lyotropic liquid crystalline state
;
helix-helix transition
;
2H-nmr method
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Poly(β-phenethyl L-aspartate) (PPLA) takes the right-handed α-helical form in 1,1,2,2-tetrachloroethane at moderate temperatures. The transition to the left-handed α-helix occurs at around 85°C in the isotropic solution as well as in the lyotropic liquid crystalline state. In the presence of a denaturant acid, PPLA also exhibits a transformation to the left-handed form by lowering temperature. Accordingly, a ternary mixture such as PPLA trifluoroacetic acid/chloroform possibly exhibits as many as five phases above certain concentration. The primary cause responsible for such a highly cooperative helix-helix transition was found to reside in a small free-energy difference in the conformational states of the side chain flanking the spiral backbone of the two opposite handedness. © 1998 John Wiley & Sons, Inc. Biopoly 43: 405-412, 1997
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
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