Abaskharon Rachel M, Brown Stephen P, Zhang Wenkai, Chen Jianxin, Smith Amos B, Gai Feng
Department of Chemistry, University of Pennsylvania, 231 South 34 Street, Philadelphia, PA 19104, USA.
Ultrafast Optical Processes Laboratory, University of Pennsylvania, 231 South 34 Street, Philadelphia, PA 19104, USA.
Chem Phys Lett. 2017 Sep 1;683:193-198. doi: 10.1016/j.cplett.2017.03.064. Epub 2017 Mar 23.
Because of their negatively charged carboxylates, aspartate and glutamate are frequently found at the active or binding site of proteins. However, studying a specific carboxylate in proteins that contain multiple aspartates and/or glutamates via infrared spectroscopy is difficult due to spectral overlap. We show, herein, that isotopic-labeling of the aspartate sidechain can overcome this limitation as the resultant C=O asymmetric stretching vibration resides in a transparent region of the protein IR spectrum. Applicability of this site-specific vibrational probe is demonstrated by using it to assess the dynamics of an aspartate ion buried inside a small protein via two-dimensional infrared spectroscopy.
由于天冬氨酸和谷氨酸带有带负电荷的羧酸盐，它们经常出现在蛋白质的活性或结合位点。然而，由于光谱重叠，通过红外光谱研究含有多个天冬氨酸和/或谷氨酸的蛋白质中的特定羧酸盐很困难。我们在此表明，天冬氨酸侧链的同位素标记可以克服这一限制，因为由此产生的C=O不对称伸缩振动位于蛋白质红外光谱的透明区域。通过使用这种位点特异性振动探针通过二维红外光谱评估埋在小蛋白质内部的天冬氨酸离子的动力学，证明了该探针的适用性。
