Energy Transfer to the Phonons of A Macromolecule Through Light Pumping

" The aim of the present paper is to understand ... how can we better describe the process of conversion of the photon energy received through electronic excitation of the fluorophores attached to a biomolecule (protein) into vibrational energy of the chain of subunits (amino acids) composing it." {Credits 1}

" The relevance of this out-of-equilibrium collective molecular vibrations consists in the possibility of activating long-range electrodynamic interactions between bio-macromolecules [2]. The reason is that, at thermal equilibrium, a macromolecule vibrates incoherently with a broad spectrum of modes, whereas the action of an external source of energy promoting a phenomenon of phonon condensation can induce the coherent motion of the molecular subunits, so that, the resulting collective vibration can bring about a large oscillating dipole moment. Under this condition long-range and resonant (thus selective) electrodynamic forces can be activated. In turn, these electrodynamic forces could help explaining the astonishing efficiency of the impressively complex biochemical machinery at work in living cells [3], where the different actors (proteins, DNA and RNA) find their cognate partners and targets in the right place, at the right time and in the right sequence in an overcrowded environment (the cytosol)." {Credits 1}

" Of course we are faced with the problem of understanding what might replace the laser action in living cells. There are several possible candidates to play the role of external energy suppliers, for instance, the hydrolysis of Adenosine Triphosphate (ATP) releases a highly energetic phosphate group, redox reactions and mitochondria produce weak UV photons that might excite Tryptophan and Tyrosine amino acids9, 10 in proteins, as well nucleotides of DNA and RNA. Also an anisotropic momentum transfer operated by water molecules or ions could make the job11. In either cases of metabolically generated photons or of ion collisions (phosphate stemming from ATP hydrolysis or other) we can assume that the external energy input for a biomolecule occurs through the generation of "hot points", as in the case of light activated fluorophores, and mediated by either radiative or collisional electronic excitation." {Credits 1}

{Credits 1} 🎪 Faraji, E., Franzosi, R., Mancini, S., & Pettini, M. (2020). Energy transfer to the phonons of a macromolecule through light pumping. © 2020 The Author(s). This open access article is distributed under Creative Commons Attribution License.