Department of Physics, and Program of Biophysics, The Ohio State University, Columbus, Ohio 43210, USA.
J Am Chem Soc. 2012 Oct 10;134(40):16460-3. doi: 10.1021/ja305283j. Epub 2012 Sep 26.
Water motion probed by intrinsic tryptophan shows the significant slowdown around protein surfaces, but it is unknown how the ultrafast internal conversion of two nearly degenerate states of Trp ((1)L(a) and (1)L(b)) affects the initial hydration in proteins. Here, we used a mini-protein with 10 different tryptophan locations one at a time through site-directed mutagenesis and extensively characterized the conversion dynamics of the two states. We observed all the conversion time scales in 40-80 fs by measurement of their anisotropy dynamics. This result is significant and shows no noticeable effect on the initial observed hydration dynamics and unambiguously validates the slowdown of hydration layer dynamics as shown here again in two mutant proteins.
色氨酸固有荧光探测到水的运动在蛋白质表面显著减速，但超快的色氨酸（（1）L(a) 和（1）L(b)）两个几乎简并态的内部转换如何影响蛋白质的初始水合作用尚不清楚。在这里，我们使用一个通过定点突变得到的含有 10 个不同色氨酸的小蛋白，分别对这两种状态的转换动力学进行了广泛的研究。通过各向异性动力学的测量，我们观察到所有的转换时间尺度都在 40-80 fs 之间。这一结果意义重大，没有对初始观察到的水合动力学产生明显影响，并再次明确验证了水合层动力学的减速作用。
