INSIGHTS INTO HEME STRUCTURE FROM SORET EXCITATION RAMAN-SPECTROSCOPY
INSIGHTS INTO HEME STRUCTURE FROM SORET EXCITATION RAMAN-SPECTROSCOPY
复制标题
DOI：
10.1021/bi00507a048
复制
发表时间：
1981-01-01
期刊：
影响因子：
2.9
通讯作者：
BABCOCK, GT
中科院分区：
文献类型：
--
作者：
CALLAHAN, PM;BABCOCK, GT
利用与Soret波段光学跃迁共振的激光谱线，获得了几种血红素蛋白和血红素模型化合物的拉曼光谱。在1560 ~ 1600cm -1范围内偏振模式的观测频率与血红素Fe自旋和配位几何之间存在相关性。该带的位置也与卟啉吡咯环的构型有关。-碳取代，只有在考虑了这种依赖关系后，才能从拉曼数据中提取结构信息。在三种常见的血红素化合物中，该波段的频率与卟啉核大小之间存在定量相关性：原血红素衍生物、所有环位都饱和的铁卟啉和血红素a种。在这些化合物的Soret激发下，1470-1510 cm-1区域的极化模式持续增强，但对周围取代基相对不敏感，可以与上述极化模式结合使用来分配血红素几何形状。在1600 cm-1以上的频率区域，观察到响应卟啉几何形状变化的振动。这个波段有时被不饱和的振动所掩盖。-碳取代基，特别是原血红素衍生物。采用Abe等人提出的法向坐标分析来合理化各种模式对卟啉几何形状和外周替代的依赖性。
Laser lines in resonance with the Soret band optical transitions of several heme proteins and heme model compounds were used to obtain Raman spectra of these species. Correlations between the observed frequency of a polarized mode in the 1560-1600 cm-1 region and the heme Fe spin and coordination geometry were developed. The position of this band is also a function of the pattern of porphyrin pyrrole ring .beta.-carbon substitution, and structural information can be extracted from the Raman data only after this dependence has been taken into account. Quantitative correlations between the frequency of this band and the porphyrin core size are presented for 3 commonly occurring classes of heme compounds: protoheme derivatives, Fe porphyrins in which all ring positions are saturated and heme a species. A polarized mode in the 1470-1510 cm-1 region is consistently enhanced upon Soret excitation of these compounds, but is relatively insensitive to peripheral substituents and can be used in conjunction with the polarized mode described above to assign heme geometries. In the frequency region above 1600 cm-1, a vibration is observed which responds to changes in porphyrin geometry. This band is sometimes obscured by vibrations of unsaturated .beta.-carbon substituents, particularly in the case of protoheme derivatives. The normal coordinate analysis developed by Abe and co-workers is used to rationalize the dependence of the various modes on porphyrin geometry and peripheral substitution.