Manor Joshua, Feldblum Esther S, Zanni Martin T, Arkin Isaiah T
The Alexander Silberman Institute of Life Sciences. Department of Biological Chemistry. The Hebrew University of Jerusalem, Edmund J. Safra Campus, Jerusalem, 91904, Israel.
J Phys Chem Lett. 2012 Mar 12;3(7):939-944. doi: 10.1021/jz300150v.
The polarity pattern of a macromolecule is of utmost importance to its structure and function. For example, one of the main driving forces for protein folding is the burial of hydrophobic residues. Yet polarity remains a difficult property to measure experimentally, due in part to its non-uniformity in the protein interior. Herein, we show that FTIR linewidth analysis of noninvasive 1-(13)C=(18)O labels can be used to obtain a reliable measure of the local polarity, even in a highly multi-phasic system, such as a membrane protein. We show that in the Influenza M2 H(+) channel, residues that line the pore are located in an environment that is as polar as fully solvated residues, while residues that face the lipid acyl chains are located in an apolar environment. Taken together, FTIR linewidth analysis is a powerful, yet chemically non-perturbing approach to examine one of the most important properties in proteins - polarity.
大分子的极性模式对其结构和功能至关重要。例如，蛋白质折叠的主要驱动力之一是疏水残基的埋藏。然而，极性仍然是一个难以通过实验测量的性质，部分原因是其在蛋白质内部的不均匀性。在此，我们表明，即使在高度多相的系统（如膜蛋白）中，对非侵入性的1-(13)C=(18)O标记进行傅里叶变换红外光谱（FTIR）线宽分析，也可用于获得局部极性的可靠测量值。我们表明，在流感M2 H(+)通道中，构成孔道的残基所处环境的极性与完全溶剂化的残基相同，而面向脂质酰基链的残基则处于非极性环境中。综上所述，FTIR线宽分析是一种强大且化学性质不干扰的方法，可用于研究蛋白质中最重要的性质之一——极性。
