TY - JOUR

T1 - Molecular rotational correlation times and nanoviscosity determined by 111mCd perturbed angular correlation (PAC) of γ‐rays spectroscopy

AU - Fromsejer, Rasmus

AU - Jensen, Marianne L.

AU - Zacate, Matthew O.

AU - Karner, Victoria

AU - Pecoraro, Vincent L.

AU - Hemmingsen, Lars

PY - 2023

Y1 - 2023

N2 - 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.

AB - 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.

U2 - 10.1002/chem.202203084

DO - 10.1002/chem.202203084

M3 - Journal article

C2 - 36453728

VL - 29

JO - Chemistry: A European Journal

JF - Chemistry: A European Journal

SN - 0947-6539

IS - 9

M1 - e202203084

ER -