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Investigating Functional Dynamics in Proteins by Novel Multidimensional Optical Spectroscopies in the Ultraviolet

Final Report Summary - FUNCTIONALDYNA (Investigating Functional Dynamics in Proteins by Novel Multidimensional Optical Spectroscopies in the Ultraviolet)

Proteins perform their biological function following specific sequences of events. During these dynamical paths, highly non-trivial cooperative interactions occur. Ultimately, this is the origin of the emerging collective behavior that makes proteins the most sophisticated existing molecular machines. The main goal of the project was to investigate long-range interactions in few selected systems by means of advanced fs time-resolved (ultrafast) spectroscopies. Specifically I extended emerging multidimensional ultrafast optical spectroscopic techniques to the deep ultraviolet. These techniques are the analogue of multidimensional Nuclear Magnetic Resonance methods and are able to provide structural information exploiting electric dipole couplings but with fs temporal resolution. The novel extension to ultraviolet has opened the possibility to exploit the optical absorption of aromatic amino-acid residues with the great advantage of studying directly also wild type proteins, without need of artificial labelling. I have used this new technique to study site-site interactions in ET proteins (blue-copper proteins) but also in multichromophoric light-harvesting antenna and emerging functional material as carbon nanodots. We identified new mechanisms for efficient and ultrafast energy transfer over long distances in multichromophoric systems. This outcome suggests new strategies to design more efficient light-harvesting antenna for photocatalysis and can be relevant to the design of artificial leaves for the production of solar fuels. We definitively clarified the origin of the optical properties of a novel family of functional materials as carbon dots, which has potentials to complement or even replace semiconductor nanoparticles in several applications and domains, in particular where bio-toxicity is an issue. In ET proteins we succeeded to observe signature of the coupling between two amino acids, one on the two being for sure functionally relevant. This first result lays the foundations of a more extensive study to comprehend the role of environmental and structural conditions on these couplings and on the ET function.