ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A series of sequential polypeptides (LysiRj)n (R is Leu, Ser, or Gly) and random copolypeptides, (Lysx, Leuy)n, were synthesized. Their conformation in NaDodSO4 solution was determined by CD. Only (Lys-Leu)n, (Lys-Ser)n, and (Lys3-Ser)n adopt a stable β-form in the surfactant solution; (Lys-Ser2)n, (Lys-Ser3)n, (Lys2-Ser2)n, and (Lys2-Ser)n have an unstable β-form, which reverts to an unordered form in high NaDodSO4 concentrations, even though both Ser and DodSO4--bound Lys+ are β-formers. In contrast, (Lys-Gly)n remains unordered in NaDodSO4 solution. On the other hand, Lys-rich (Lys2-Leu)n forms an unstable helix and (Lys2-Leu2)n a stable helix in NaDodSO4 solution. In 25 mM NaDodSO4 (Lysx, Leuy)n also forms a helix up to x = 75 and reverts to the β-form at x = 90. This compares with the helical conformation of (Lysx, Alay)n up to x = 65 and its β-form at x = 90, suggesting that Leu is an even stronger helix-former than Ala. Our results may provide a plausible explanation for the increase in helicity and disruption of the β-form for many proteins in NaDodSO4 solution, that is, the polypeptide chain of a protein usually favors a helical conformation over a β-form in the presence of excess surfactant.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360221009
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