Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photo Switching of Protein Dynamical Collectivity   We examine changes in the picosecond structural dynamics with irreversible
photobleaching of red fluorescent proteins mCherry, mOrange2 and TagRFP-T.
Measurements of the protein dynamical transition using terahertz time-domain
spectroscopy show in all cases an increase in the turn-on temperature in the
bleached state. The result is surprising given that there is little change in
the protein surface, and thus the solvent dynamics held responsible for the
transition should not change. A spectral analysis of the measurements guided by
quasiharmonic calculations of the protein absorbance reveals that indeed the
solvent dynamical turn-on temperature is independent of the thermal stability
and photostate however the protein dynamical turn-on temperature shifts to
higher temperatures. This is the first demonstration of switching the protein
dynamical turn-on temperature with protein functional state. The observed shift
in protein dynamical turn-on temperature relative to the solvent indicates an
increase in the required mobile waters necessary for the protein picosecond
motions: that is these motions are more collective. Melting-point measurements
reveal that the photobleached state is more thermally stable and structural
analysis of related RFPs shows that there is an increase in internal water
channels as well as a more uniform atomic root mean squared displacement. These
observations are consistent with previous suggestions that water channels form
with extended light excitation providing O2 access to the chromophore and
subsequent fluorescence loss. We report that these same channels increase
internal coupling enhancing thermal stability and collectivity of the
picosecond protein motions. The terahertz spectroscopic characterization of the
protein and solvent dynamical onsets can be applied generally to measure
changes in collectivity of protein motions.

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The categories of this paper are: math-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: math
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: gr-qc
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The categories of this paper are: mtrl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: hep-lat