The folding of randomly coiled poly(bg1utamic acid) to the helical state has been studied in N-methylacetamide by titration methods. Since this solvent would be expected to form amide-peptide group hydrogen bonds with the unfolded form of the polymer, to a first approximation no helix stabilization
Specific helix stabilization of poly(L-glutamic acid) in mixed counterion systems
β Scribed by Mitsuru Satoh; Fusaaki Kato; Jiro Komiyama
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1993
- Tongue
- English
- Weight
- 676 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0006-3525
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β¦ Synopsis
The coil-helix transitions of poly (L-glutamic acid) in aqueous alcohol solutions have been investigated for mixed counterion systems. It has been found that coexistence of two kinds of counterion species, i.e., two alkali metal counterions, alkali and alkaline earth metal, and two alkaline earth metals, specifically stabilizes or destabilizes the helix conformation depending upon the combination of the counterion species. The most striking enhancement of the helix content was observed for the combination of Lit and K + counterions. It has been suggested that the helix stabilization is attributed to the reduction of the free energy in the contact ion pair formation between the polymer charges and the counterions in the mixed counterion systems.
π SIMILAR VOLUMES
The anisotropic rotational motion of the backbone and the side chains of poly(t glutamic acid) in the a-helical structure was investigated using the ' G T , and T2 relaxation times of all carbon atoms with directly attached protons, obtained at a I T -Larmor frequency of 67.89 MHz. The evaluation of
The helix-coil transit.iotis for poly(L-glutamic acid) (PGA) in 0.2M NaCl and ill its mixture with dioxane were studied by the methods of spectropolarimetry, viscometry, and potentiometric titration at different temperatures from 8 to 50Β°C. The enthalpy and entropy differences between the helical an
A series of poly(cg1utamic acid) esters have been synthesized and studied by optical rotatory dispersion, x-ray diffraction, and infrared spectrometry. The results obtained emphasize the importance of the outer portions of the side chains in determining both the stability and precise conformation of