Serrano Vesna, Liu Wenge, Franzen Stefan
Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA.
Biophys J. 2007 Oct 1;93(7):2429-35. doi: 10.1529/biophysj.106.100594. Epub 2007 Jun 1.
The infrared spectroscopy of elastin-like polypeptides and the relation to the inverse thermal transition are discussed. To correlate the spectroscopic observations with structure a density function theory model was created that captures the essential hydrogen bonding and packing of the beta-spiral structure proposed for elastin and elastin-like polypeptides. The infrared spectrum was calculated using periodic boundary conditions and a method for estimating the difference dipole moment permits both frequencies and intensities to be obtained for the modeling of spectra. The two observed amide I bands at 1615 cm(-1) and 1656 cm(-1) are shown to arise from the beta-spiral structure. The increase in intensity of these bands with increasing salt concentration and temperature is assigned to the closer association of strands of the beta-spiral. The sharp inverse temperature transition is observed within 1 degrees C and involves a change in secondary structure that involves formation of interstrand beta-sheets for approximately 25% of the amino acids. This conclusion is consistent with available data and simulations that have been reported to date.
讨论了类弹性蛋白多肽的红外光谱及其与反向热转变的关系。为了将光谱观测结果与结构相关联，创建了一个密度泛函理论模型，该模型捕捉了为弹性蛋白和类弹性蛋白多肽提出的β-螺旋结构的基本氢键和堆积情况。使用周期性边界条件计算红外光谱，一种估计差分偶极矩的方法允许获得用于光谱建模的频率和强度。在1615 cm(-1) 和1656 cm(-1) 处观察到的两个酰胺I谱带显示源自β-螺旋结构。这些谱带的强度随盐浓度和温度的增加而增加，这归因于β-螺旋链的更紧密缔合。在1摄氏度范围内观察到急剧的逆温度转变，涉及二级结构的变化，约25% 的氨基酸形成链间β-折叠。这一结论与迄今为止报道的现有数据和模拟结果一致。
