STUDIES OF SYNTHETIC HELICAL PEPTIDES USING CIRCULAR-DICHROISM AND NUCLEAR-MAGNETIC-RESONANCE
STUDIES OF SYNTHETIC HELICAL PEPTIDES USING CIRCULAR-DICHROISM AND NUCLEAR-MAGNETIC-RESONANCE
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DOI：
10.1016/s0022-2836(05)80172-x
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发表时间：
1990-10-20
影响因子：
5.6
通讯作者：
KUNTZ, ID
中科院分区：
文献类型：
--
作者：
BRADLEY, EK;THOMASON, JF;KUNTZ, ID
我们设计了一组17个残基的合成肽，在水溶液中形成单体螺旋。圆二色性实验表明，在低温和低pH下，水溶液中存在螺旋结构。其中一种肽的二维核磁共振结果显示了10个残基的片段，该片段明显满足在5 ° C和5 ° C下存在螺旋结构的所有标准。C和15度。C.肽的前四个残基处于大部分延伸的构象。计算表明，残基5至14在5 °处是显著螺旋的。C.圆二色光谱表明，随着温度的升高，螺旋含量降低。在15度。C，3JN.alpha。耦合常数在螺旋区域中增加，表明螺旋片段中运动或构象平均化的增加。没有肽具有与螺旋构象的盐桥稳定一致的pH滴定行为。我们的数据有助于解释与螺旋偶极子模型和特定的侧链相互作用。当N和C末端电荷被去除时，肽的螺旋含量增加。由于His16的电离，螺旋度的量随着pH降低而增加。大部分的螺旋稳定似乎是由于一个特定的侧链之间的相互作用His16和Tyr12。
We have designed a set of 17-residue synthetic peptides to be monomeric helices in acqueous solution. Circular dichroism experiments indicate the presence of helical structure in aqueous solution at low temperature and low pH. The two-dimensional nuclear magnetic resonance results for one of the peptides show a segment of ten residues which clearly meets all of the criteria for the existence of helical structure at both 5.degree. C and 15.degree. C. The first four residues of the peptide are in a largely extended conformation. Calculations suggest that residues 5 through 14 are significantly helical at 5.degree. C. When the temperature is increased, circular dichroism spectra indicate that the helical content decreases. At 15.degree. C, the 3JN.alpha. coupling constants increase in the helical region, indicating an increase in motion or conformational averaging in the helical segment. None of the peptides has pH titration behavior consistent with salt bridge stabilization of helical conformation. Our data lend themselves to interpretation with the helix dipole model and specific side-chain interactions. When the N and C termini charges are removed the helical content of the peptides increases. The amount of helicity increases as the pH is lowered, due to the ionization of His16. Much of the helical stabilization appears to be due to a specific side-chain interaction between His16 and Tyr12.