Stabilization of the ribonuclease S-peptide alpha-helix by trifluoroethanol.
Stabilization of the ribonuclease S-peptide alpha-helix by trifluoroethanol.
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发表时间：
1986
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通讯作者：
J. W. Nelson;N. Kallenbach
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作者：
J. W. Nelson;N. Kallenbach
通过测量圆二色性作为 TFE 浓度、pH 和温度的函数，研究了三氟乙醇 (TFE) 对核糖核酸酶 S 肽形成的 α 螺旋（核糖核酸酶 A 的残基 1-19）稳定性的影响。 S 肽形成异常稳定的 α 螺旋，已知 TFE 可以稳定该螺旋。带电基团对肽的影响大小（通过 α 螺旋稳定性随 pH 值变化而变化而体现）并未因 TFE 浓度或温度而显着改变，表明 TFE 的较低介电常数对于该 α 螺旋的稳定并不重要。这表明除了电荷的影响之外，α-螺旋还可能通过许多相互作用来稳定。圆二色性与 TFE 浓度的滴定曲线在 0°C 时似乎是协调的，但在 25 至 75°C 之间的温度下，协调性逐渐减弱。TFE 稳定的特性表明，TFE 可能是一种有用的探针，可用于测量边缘稳定的肽和小蛋白质的稳定性。
The effects of trifluoroethanol (TFE) on the stability of the alpha-helix formed by ribonuclease S-peptide, residues 1-19 of ribonuclease A, were studied by measuring circular dichroism as a function of TFE concentration, pH, and temperature. The S-peptide forms an unusually stable alpha-helix, which is known to be stabilized by TFE. The magnitude of the effect of charged groups on the peptide, manifested by the change in alpha-helix stability as a function of pH, was not altered significantly by either TFE concentration or temperature, indicating that the lower dielectric constant of TFE is not important in the stabilization of this alpha-helix. This suggests that the alpha-helix might be stabilized by many interactions in addition to the effects of charges. The titration curve of circular dichroism vs. TFE concentration appears to be cooperative at 0 degree C, but becomes progressively less cooperative at temperatures between 25 and 75 degrees C. The properties of the TFE stabilization indicate that TFE might be a useful probe with which to measure the stability of marginally stable peptides and small proteins.