Tubulin Vibration Modes Are in the Subterahertz Range, and Their Electromagnetic Absorption Is Affected by Water

Many
proteins are thought to coordinate distant sites
in their
structures through a concerted action of global structural vibrations.
However, the direct experimental spectroscopic detection of these
vibration modes is rather elusive. We used normal-mode analysis to
explore the dominant vibration modes of an all-atom model of the tubulin
protein and described their characteristics using a large ensemble
of tubulin structures. We quantified the frequency range of the normal
vibrational modes to be in the subterahertz band, specifically between
∼40 and ∼160 GHz. Adding water layers to the model increases
the frequencies of the low-frequency modes and narrows the frequency
variations of the modes among the protein ensemble. We also showed
how the electromagnetic absorption of tubulin vibration modes is affected
by vibrational damping. These results contribute to our understanding
of tubulin’s vibrational and electromagnetic properties and
provide a foundation for future attempts to control protein behavior
via external electromagnetic fields.