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Functional-State Dependence of Picosecond Protein Dynamics.

The journal of physical chemistry. B (2021-10-05)
D K George, J Y Chen, Yunfen He, J R Knab, A G Markelz
ABSTRACT

We examine temperature-dependent picosecond dynamics of two benchmarking proteins lysozyme and cytochrome c using temperature-dependent terahertz permittivity measurements. We find that a double Arrhenius temperature dependence with activation energies E1 ∼ 0.1 kJ/mol and E2 ∼ 10 kJ/mol fits the folded and ligand-free state response. The higher activation energy is consistent with the so-called protein dynamical transition associated with beta relaxations at the solvent-protein interface. The lower activation energy is consistent with correlated structural motions. When the structure is removed by denaturing, the lower-activation-energy process is no longer present. Additionally, the lower-activation-energy process is diminished with ligand binding but not for changes in the internal oxidation state. We suggest that the lower-energy activation process is associated with collective structural motions that are no longer accessible with denaturing or binding.

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Sigma-Aldrich
Lisozima, powder or granules, ≥90 %, ≥39,000 units/mg protein
Sigma-Aldrich
Citocromo c, ≥95% (SDS-PAGE)
Sigma-Aldrich
Citocromo c, ≥95% based on Mol. Wt. 12,327 basis