酰胺II'脯氨酸拉曼带对肽构象的依赖性。
Dependence of the AmII'p proline Raman band on peptide conformation.
作者信息
Ahmed Zeeshan, Myshakina Nataliya S, Asher Sanford A
机构信息
Department of Chemistry, University of Pittsburgh, Pennsylvania 15260, USA.
出版信息
J Phys Chem B. 2009 Aug 13;113(32):11252-9. doi: 10.1021/jp809857y.
We utilized UV resonance Raman (UVRR) measurements and density functional theory (DFT) calculations to relate the AmII'p frequency to the psi angle. The AmII'p frequency shifts by approximately 25 cm(-1) as the psi angle is varied over allowed angles of the Pro peptide bond. The AmII'p frequency does not show any significant dependence on the phi dihedral angle. The conformation sensitivity of the AmII'p frequency derives from conformation-induced changes in the planarity of the Pro peptide bond; psi angle changes push the amide nitrogen out of the peptide bond plane. We use this AmII'p frequency dependence on the psi angle to track temperature-induced conformation changes in a polyproline peptide. The temperature-induced 7 cm(-1) downshift in the AmII'p frequency of the polyproline peptide results from an approximately 45 degrees rotation of the psi dihedral angle from psi = 145 degrees (ideal PPII conformation) to psi = 100 degrees (collapsed PPII conformation).
我们利用紫外共振拉曼（UVRR）测量和密度泛函理论（DFT）计算，将AmII'p频率与ψ角联系起来。当ψ角在脯氨酸肽键的允许角度范围内变化时，AmII'p频率会发生约25 cm⁻¹的偏移。AmII'p频率对φ二面角没有任何显著依赖性。AmII'p频率的构象敏感性源于脯氨酸肽键平面度的构象诱导变化；ψ角的变化将酰胺氮推出肽键平面。我们利用这种AmII'p频率对ψ角的依赖性来追踪聚脯氨酸肽中温度诱导的构象变化。聚脯氨酸肽的AmII'p频率因温度诱导而下降7 cm⁻¹，这是由于ψ二面角从ψ = 145°（理想的PPII构象）旋转到ψ = 100°（塌陷的PPII构象）约45°所致。
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