Conformations of alanine-based peptides in water probed by FTIR, Raman, vibrational circular dichroism, electronic circular dichroism, and NMR spectroscopy.
Conformations of alanine-based peptides in water probed by FTIR, Raman, vibrational circular dichroism, electronic circular dichroism, and NMR spectroscopy.
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DOI：
10.1021/bi062224l
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发表时间：
2007-01
期刊：
影响因子：
2.9
通讯作者：
R. Schweitzer‐Stenner;T. Measey;L. Kakalis;F. Jordan;S. Pizzanelli;C. Forte;K. Griebenow
中科院分区：
文献类型：
--
作者：
R. Schweitzer‐Stenner;T. Measey;L. Kakalis;F. Jordan;S. Pizzanelli;C. Forte;K. Griebenow
我们使用FTIR、VCD、ECD、拉曼和NMR光谱的组合来探测由H-（AAKA）-OH取样的溶液构象，通过利用激子耦合模型和由中心残基的3 J CalphaHNH耦合常数施加的约束来模拟IR、各向同性拉曼、各向异性拉曼和VCD光谱的酰胺I'轮廓，其根据三种构象的混合物，即，聚脯氨酸II、β-链和右旋螺旋。三种构象的代表性坐标是从公布的线圈库中获得的。发现丙氨酸表现出0.60或更大的PPII分数，与较小分数的螺旋和β-链构象混合。赖氨酸没有表现出明确的构象倾向，因为它的样品聚脯氨酸II，β-链，螺旋构象具有可比的概率。这是在差异与离子化聚赖氨酸，这表明一个高的聚脯氨酸II的倾向得到较早的结果。我们重新分析了以前研究的四和三丙氨酸结合出版的振动光谱数据与3 JCalphaHNH耦合常数，并再次获得由PPII为主的混合物与较小的混合物的β-链和右手螺旋构象。丙氨酸的聚脯氨酸II倾向被认为是在四丙氨酸比在三丙氨酸。对于所有的肽研究，我们的研究结果排除了大量人口的转向样构象。我们的结果与Gnanakaran和Garcia对短丙氨酸肽的MD模拟非常一致[（2003）J. Phys. Chem. B 107，12555-12557]，但与多个MD模拟不同，特别是对于丙氨酸二肽。
We have used a combination of FTIR, VCD, ECD, Raman, and NMR spectroscopies to probe the solution conformations sampled by H-(AAKA)-OH by utilizing an excitonic coupling model and constraints imposed by the 3JCalphaHNH coupling constants of the central residues to simulate the amide I' profile of the IR, isotropic Raman, anisotropic Raman, and VCD spectra in terms of a mixture of three conformations, i.e., polyproline II, beta-strand and right-handed helical. The representative coordinates of the three conformations were obtained from published coil libraries. Alanine was found to exhibit PPII fractions of 0.60 or greater, mixed with smaller fractions of helices and beta-strand conformations. Lysine showed no clear conformational propensity in that it samples polyproline II, beta-strand, and helical conformations with comparable probability. This is at variance with results obtained earlier for ionized polylysine, which suggest a high polyproline II propensity. We reanalyzed previously investigated tetra- and trialanine by combining published vibrational spectroscopy data with 3JCalphaHNH coupling constants and obtained again blends dominated by PPII with smaller admixtures of beta-strand and right-handed helical conformations. The polyproline II propensity of alanine was found to be higher in tetraalanine than in trialanine. For all peptides investigated, our results rule out a substantial population of turn-like conformations. Our results are in excellent agreement with MD simulations on short alanine peptides by Gnanakaran and Garcia [(2003) J. Phys. Chem. B 107, 12555-12557] but at variance with multiple MD simulations particularly for the alanine dipeptide.