Descrizione del progetto
Misurare le forze elettriche tra le molecole biologiche e il loro ambiente
Le cariche opposte si attraggono, mentre le cariche simili si respingono: questo fenomeno è piuttosto facile da osservare e da misurare durante un semplice esperimento di fisica a livello di scuola superiore utilizzando palloncini e l’elettricità statica. Tuttavia, ciò risulta molto più difficile quando si tratta di molecole biologiche cariche nel loro ambiente naturale, ossia la soluzione fisiologica, che consiste di molecole polari di acqua e ioni caricati positivamente. Il progetto BIOVIB, finanziato dall’UE, darà uno sguardo più approfondito e inedito alle molecole idratate di RNA e DNA, le cui vibrazioni di base esaminano in modo diretto le interazioni intermolecolari e intramolecolari. Avvalendosi della spettroscopia ad alta tecnologia e di campi elettrici THz applicati esternamente, gli scienziati intendono aprire un nuovo spiraglio sulle forze elettriche che trainano e spingono le molecole biologiche.
Obiettivo
Biomolecules exist in an aqueous environment of dipolar water molecules and solvated ions. Their structure and biological function are strongly influenced by electric interactions with the fluctuating water shell and ion atmosphere. Understanding such interactions at the molecular level is a major scientific challenge; presently, their strengths, spatial range and interplay with other non-covalent interactions are barely known. Going far beyond existing methods, this project introduces the new paradigm of a direct time-resolved mapping of molecular electric forces on sub-nanometer length scales and at the genuine terahertz (THz) fluctuation frequencies. Vibrational excitations of biomolecules at the interface to the water shell act as sensitive noninvasive probes of charge dynamics and local electric fields. The new method of time resolved vibrational Stark shift spectroscopy with THz external fields calibrates vibrational frequencies as a function of absolute field strength and separates instantaneous from retarded environment fields. Based on this knowledge, multidimensional vibrational spectroscopy gives quantitative insight in the biomolecular response to electric fields, discerning contributions from water and ions in a site-specific way. The experiments and theoretical analysis focus on single- and double-stranded RNA and DNA structures at different hydration levels and with ion atmospheres of controlled composition, structurally characterized by x-ray scattering. As a ground-breaking open problem, the role of magnesium and other ions in RNA structure definition and folding will be addressed by following RNA folding processes with vibrational probes up to milliseconds. The impact of site-bound versus outer ions will be dynamically separated to unravel mechanisms stabilizing secondary and tertiary RNA structures. Beyond RNA research, the present approach holds strong potential for fundamental insight in transmembrane ion channels and channel rhodopsins.
Campo scientifico
Parole chiave
Programma(i)
Argomento(i)
Meccanismo di finanziamento
ERC-ADG - Advanced GrantIstituzione ospitante
12489 Berlin
Germania