可以通过测量分子旋转相关时间来确定溶液中分子所经历的纳米粘度。τc,例如,通过荧光和核磁共振光谱。有了这项工作,我们应用PAC光谱来确定旋转扩散的速率,λ=1/τc,从头设计的蛋白质,TRIL12AL16C,在具有粘性的溶液中,ζ,从1.7到88mPa·s。TRIL12AL16C被选为分子探针,因为它由于分子内动力学和静态线宽而表现出最小的影响,允许分子旋转扩散的独家阐明。由PAC数据确定的扩散速率与荧光和NMR光谱的文献数据非常吻合,与斯托克斯-爱因斯坦-德拜模型一致,线性缩放比例为1/ζ。PAC实验仅需要痕量(〜1011)的探针核,并且可以在宽范围的样品温度和压力下进行。此外,大多数材料对γ射线相对透明。因此,PAC光谱学可以在传统技术无法应用的情况下找到应用,从液体物理学到体内生物化学。
The nanoviscosity experienced by molecules in solution may be determined through measurement of the molecular rotational correlation time, τc , for example, by fluorescence and NMR spectroscopy. With this work, we apply PAC spectroscopy to determine the rate of rotational diffusion, λ=1/τc , of a de novo designed protein, TRIL12AL16C, in solutions with viscosities, ξ, from 1.7 to 88 mPa⋅s. TRIL12AL16C was selected as molecular probe because it exhibits minimal effects due to intramolecular dynamics and static line broadening, allowing for exclusive elucidation of molecular rotational diffusion. Diffusion rates determined by PAC data agree well with literature data from fluorescence and NMR spectroscopy, and scales linearly with 1/ξ in agreement with the Stokes-Einstein-Debye model. PAC experiments require only trace amounts (∼1011 ) of probe nuclei and can be conducted over a broad range of sample temperatures and pressures. Moreover, most materials are relatively transparent to γ-rays. Thus, PAC spectroscopy could find applications under circumstances where conventional techniques cannot be applied, spanning from the physics of liquids to in-vivo biochemistry.