Folding and unfolding of helix-turn-helix motifs in the gas phase.
Folding and unfolding of helix-turn-helix motifs in the gas phase.
复制标题
气相中螺旋-转角-螺旋图案的折叠和展开。
DOI：
10.1016/j.jasms.2007.03.027
复制
发表时间：
2007
影响因子：
3.2
通讯作者：
Jarrold,MartinF
中科院分区：
文献类型：
--
作者：
Zilch,LloydW;Kaleta,DavidT;Kohtani,Motoya;Krishnan,Ranjani;Jarrold,MartinF
对一系列设计具有螺旋-转角-螺旋基序的肽进行了离子淌度测量和分子动力学模拟。对于具有由短环区域连接的两个螺旋部分的肽：AcA14KG3A14K+2H+、AcA14KG5A14K+2H+、AcA14KG7A14K+2H+ 和 AcA14KSar3A14K+2H+（Ac = 乙酰基、A = 丙氨酸、G = 甘氨酸、Sar = 肌氨酸和 K = 赖氨酸）；具有两个反平行螺旋的卷曲螺旋几何形状是最低能量构象。随着温度升高，螺旋解耦，盘绕线圈展开。平衡常数确定为温度的函数，产生卷曲线圈展开的焓和熵变化。焓和熵的变化取决于环区域的长度和性质。对于具有三个螺旋部分的肽：质子化的 AcA14KG3A14KG3A14K；具有三个并排螺旋的卷曲螺旋束的稳定性远低于具有反平行卷曲螺旋中两个螺旋且第三个螺旋与另外两个螺旋之一共线的几何形状。
Ion mobility measurements and molecular dynamic simulations have been performed for a series of peptides designed to have helix-turn-helix motifs. For peptides with two helical sections linked by a short loop region: AcA14KG3A14K+2H+, AcA14KG5A14K+2H+, AcA14KG7A14K+2H+, and AcA14KSar3A14K+2H+(Ac = acetyl, A = alanine, G = glycine, Sar = sarcosine and K = lysine); a coiled-coil geometry with two anti-parallel helices is the lowest energy conformation. The helices uncouple and the coiled-coil unfolds as the temperature is raised. Equilibrium constants determined as a function of temperature yield enthalpy and entropy changes for the unfolding of the coiled-coil. The enthalpy and entropy changes depend on the length and nature of the loop region. For a peptide with three helical sections: protonated AcA14KG3A14KG3A14K; a coiled-coil bundle with three helices side-by-side is substantially less stable than a geometry with two helices in an antiparallel coiled-coil and the third helix collinear with one of the other two.