Spiro T G
Adv Protein Chem. 1985;37:111-59. doi: 10.1016/s0065-3233(08)60064-9.
Our understanding of metalloporphyrin resonance Raman spectra has advanced to the point where it is possible to obtain detailed information about the structure of the heme group in situ in heme proteins. The porphyrin skeletal mode frequencies can be analyzed in terms of the ligation and spin state of the heme and may provide information about protein-induced stresses. The high-frequency region of the spectrum also contains bands due to vibrations of the porphyrin peripheral substituents, which are potentially monitors of the protein contacts. In the low-frequency region, it is possible to locate bands, at least in some states of the heme protein, which are associated with vibrations of the axial ligands. They give direct information about the nature of the bonding to exogenous ligands or to the proximal protein residue. Thus, a variety of evidence is potentially available in the resonance Raman spectra from which a fairly complete picture of the heme site can be assembled for a particular protein in its various functional states. Detailed studies have been pursued for paradigmatic heme proteins, including myoglobin, hemoglobin, cytochrome c, horseradish peroxidase, and cytochrome oxidase. These studies provide a substantial data base from which the exploration of lesser known systems can be launched. Another extension of current knowledge to new frontiers is in the time domain, since pulsed lasers now make it feasible to carry out time-resolved resonance Raman studies on heme protein reactions. Time-resolved resonance Raman spectroscopy is capable of elucidating the temporal evolution of heme structure and provides a link between heme chemistry and protein dynamics. This link is being elucidated for hemoglobin and cytochrome c, where specific heme intermediates have been identified following ligand photodissociation or electron transfer.
我们对金属卟啉共振拉曼光谱的理解已经发展到能够原位获取血红素蛋白中血红素基团结构详细信息的程度。卟啉骨架模式频率可以根据血红素的配位和自旋状态进行分析，并且可能提供有关蛋白质诱导应力的信息。光谱的高频区域还包含由于卟啉周边取代基振动产生的谱带，这些谱带有可能作为蛋白质接触的监测指标。在低频区域，至少在血红素蛋白的某些状态下，可以定位与轴向配体振动相关的谱带。它们直接提供有关与外源性配体或近端蛋白质残基键合性质的信息。因此，共振拉曼光谱中可能存在各种证据，从中可以为处于各种功能状态的特定蛋白质拼凑出血红素位点的相当完整的图像。对典型的血红素蛋白，包括肌红蛋白、血红蛋白、细胞色素c、辣根过氧化物酶和细胞色素氧化酶，已经进行了详细研究。这些研究提供了一个丰富的数据库，可据此开展对鲜为人知系统的探索。当前知识向新领域的另一个扩展是在时域方面，因为脉冲激光器现在使对血红素蛋白反应进行时间分辨共振拉曼研究成为可能。时间分辨共振拉曼光谱能够阐明血红素结构的时间演变，并在血红素化学和蛋白质动力学之间建立联系。对于血红蛋白和细胞色素c，这种联系正在得到阐明，在配体光解离或电子转移后已鉴定出特定的血红素中间体。
