ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Raman spectroscopic studies have been carried out on polymers of L-valine ranging in degree of polymerization (DP) from 2 to 930. The spectrum of the hexapeptide (DP = 6) is closely similar over the entire range 40-1750 cm-1 to those of polymers with much higher DP, and the structure is clearly shown to be that of the antiparallel pleated sheet (β-structure) by the amide I and III frequencies. The formation of a little α-helical structure occurs in polymers with DP above 500, although the amount does not appear to be a linear function of DP. The α-helical structure is unstable and readily destroyed in samples cast from trifluoroacetic acid solution. It is stabilized by the incorporation of L-alanine, a strong helix-former; polymers of the latter may in turn be forced into a α-structure in copolymers sufficiently rich in L-valine.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1978.360170110
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