Ohta Takehiro, Kitagawa Teizo
Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.
Inorg Chem. 2005 Feb 21;44(4):758-69. doi: 10.1021/ic0486318.
Specific sensing of gas molecules such as CO, NO, and O2 is a unique function of gas sensory hemoproteins, while hemoproteins carry out a wide variety of functions such as oxygen storage/transport, electron transfer, and catalysis as enzymes. It is important in gas sensory proteins that the heme domain not only recognizes its target molecule but also discriminates against other gases having similar molecular structures. Coordination of a target molecule to the heme is assumed to alter the protein conformation in the vicinity of heme, and the conformation change is propagated to the effector domain where substrate turnover, DNA binding, or interaction with a signal transduction protein is performed differently than the binding of other gases. To understand the appearance of such a specificity, we focus our attention on the ligand-protein interactions in the distal side of heme. In practice, the metal-ligand vibrations as well as internal modes of ligand and heme are measured with resonance Raman spectroscopy for wild-type and some mutant proteins with full-length or limited sensory regions. On the basis of such observations together with the knowledge currently available, we discuss the mechanism of specific sensing of a diatomic molecule in gas sensory proteins.
对一氧化碳、一氧化氮和氧气等气体分子的特异性传感是气体传感血红蛋白的独特功能，而血红蛋白还执行多种功能，如作为酶进行氧气储存/运输、电子转移和催化。在气体传感蛋白中，重要的是血红素结构域不仅要识别其目标分子，还要区分其他具有相似分子结构的气体。假定目标分子与血红素的配位会改变血红素附近的蛋白质构象，并且构象变化会传播到效应结构域，在该结构域中，底物周转、DNA结合或与信号转导蛋白的相互作用与其他气体的结合方式不同。为了理解这种特异性的出现，我们将注意力集中在血红素远端的配体 - 蛋白质相互作用上。实际上，通过共振拉曼光谱法测量野生型以及一些具有全长或有限传感区域的突变蛋白的金属 - 配体振动以及配体和血红素的内部模式。基于这些观察结果以及当前可用的知识，我们讨论了气体传感蛋白中双原子分子的特异性传感机制。
