Andrea Cannizzo

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

August 2011

IAP - Universität Bern, Investigating Functional Dynamics in Proteins by Novel Multidimensional Optical Spectroscopies in the Ultraviolet, PE4

Proteins perform their biological function following specific sequences of events. During these dynamical paths, non-trivial highly cooperative interactions occur. Ultimately, this is the origin of the emerging collective behaviour that makes proteins the most sophisticated existing molecular machines. This complex network of processes covers a wide range of timescales ranging from few fs to milliseconds. The slowest dynamics are typical of large movements of protein domains, while the fast ones pertain more to fluctuations on the atomic scales. In this context, experimental techniques that can access this wide range of times and lengths are crucial. Multidimensional Nuclear Magnetic Resonance for example allows the access to the protein domain movements by exploring the coupling between distant magnetic dipoles. The atomic scale motions, however, are completely smeared out; the extension to the nano and femto second timescales will allow recovering them. This will unveil the large number of elementary conformational steps constituting a functional event and their temporal evolution.

Our strategy is to extend emerging multidimensional ultrafast optical spectroscopies, in particular photon echo techniques, into the deep ultraviolet. These techniques are analogues of multidimensional Nuclear Magnetic Resonance methods but with much superior temporal resolution. The extension to ultraviolet, that we are implementing, will open the possibility to exploit the optical absorption of aromatic amino-acid residues with the great advantage of studying wild type proteins. In the frame of the ERC grant we will use this new technique to study dynamic-assisted long range electron transfer in blue-copper proteins and enzyme regulation in haemoglobin. These two proteins of great importance from a biological point of view have been chosen because their functions are a clear manifestation of cooperative phenomena. We are also focused on artificial molecular devices for solar energy conversion and storage.

The development of UV photon-echo techniques is an outstanding goal that goes well beyond the present state of the art. On a long term prospective this methodology has the potential to become a universal tool applicable to wild type proteins containing aromatic amino acids. Its capability to provide information on intramolecular local (thermo )dynamics will have great impact on the way of looking into biological phenomena and bio chemical reactions. We envisage that it will also proliferate to nanosciences (molecular electronics, DNA self assembling devices, nanomechanics, etc) and material sciences (e.g. organic superconductors, heterogeneous and/or inhomogenous systems as topological insulators, quantum wells, etc.)

<<