Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA.
J Inorg Biochem. 2024 Oct;259:112641. doi: 10.1016/j.jinorgbio.2024.112641. Epub 2024 Jun 17.
Over the last 50 years resonance Raman spectroscopy has become an invaluable tool for the exploration of chromophores in biological macromolecules. Among them, heme proteins and metal complexes have attracted considerable attention. This interest results from the fact that resonance Raman spectroscopy probes the vibrational dynamics of these chromophores without direct interference from the surrounding. However, the indirect influence via through-bond and through-space chromophore-protein interactions can be conveniently probed and analyzed. This review article illustrates this point by focusing on class 1 cytochrome c, a comparatively simple heme protein generally known as electron carrier in mitochondria. The article demonstrates how through selective excitation of resonance Raman active modes information about the ligation, the redox state and the spin state of the heme iron can be obtained from band positions in the Raman spectra. The investigation of intensities and depolarization ratios emerged as tools for the analysis of in-plane and out-of-plane deformations of the heme macrocycle. The article further shows how resonance Raman spectroscopy was used to characterize partially unfolded states of oxidized cytochrome c. Finally, it describes its use for exploring structural changes due to the protein's binding to anionic surfaces like cardiolipin containing membranes.
在过去的 50 年中，共振拉曼光谱已成为探索生物大分子中发色团的宝贵工具。其中，血红素蛋白和金属配合物引起了相当大的关注。这种兴趣源于这样一个事实，即共振拉曼光谱在不直接干扰周围环境的情况下探测这些发色团的振动动力学。然而，通过键和空间发色团-蛋白质相互作用的间接影响可以方便地探测和分析。本文通过聚焦于相对简单的血红素蛋白 1 型细胞色素 c 来阐明这一点，细胞色素 c 通常被认为是线粒体中的电子载体。本文演示了如何通过选择性激发共振拉曼活性模式，从拉曼光谱中的带位置获得关于血红素铁的配位、氧化还原状态和自旋状态的信息。强度和退偏比的研究成为分析血红素大环中环内和面外变形的工具。本文进一步展示了如何使用共振拉曼光谱来表征氧化细胞色素 c 的部分去折叠状态。最后，它描述了它如何用于探索由于蛋白质与阴离子表面（如含心磷脂的膜）结合而导致的结构变化。
