Lamb Don C, Arcovito Alessandro, Nienhaus Karin, Minkow Oleksandr, Draghi Federica, Brunori Maurizio, Nienhaus G Ulrich
Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Università di Roma La Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy.
Biophys Chem. 2004 Apr 1;109(1):41-58. doi: 10.1016/j.bpc.2003.10.002.
Recombination of carbon monoxide to myoglobin mutants YQR and YQRF was studied using transient infrared absorption spectroscopy and Fourier transform infrared-temperature derivative spectroscopy (FTIR-TDS). Photoproduct states B, C', C" and D associated with ligands residing in different protein cavities have been identified. After photolysis, ligands migrate to primary docking site B and subsequently rebind or escape to a secondary site (C) within the Xe4 cavity. For YQR, a global analysis of the isothermal rebinding kinetics below 160 K and the TDS data reveal a correlation between the enthalpy barriers governing the two processes. Above 120 K, a protein conformational change in both YQR and YQRF converts photoproduct C' into C" with markedly slowed kinetics. Above approximately 180 K, ligands migrate to the proximal Xe1 site (D) and also exit into the solvent, from where they rebind in a bimolecular reaction.
利用瞬态红外吸收光谱和傅里叶变换红外温度导数光谱（FTIR-TDS）研究了一氧化碳与肌红蛋白突变体YQR和YQRF的重组。已鉴定出与位于不同蛋白质腔中的配体相关的光产物状态B、C'、C''和D。光解后，配体迁移到主要对接位点B，随后重新结合或逃逸到Xe4腔内的次要位点（C）。对于YQR，对160 K以下的等温重新结合动力学和TDS数据进行的全局分析揭示了控制这两个过程的焓垒之间的相关性。在120 K以上，YQR和YQRF中的蛋白质构象变化将光产物C'转化为C''，动力学明显减慢。在大约180 K以上，配体迁移到近端Xe1位点（D），也进入溶剂，然后在双分子反应中重新结合。
