The article presents a new interpretation of neutron scattering spectra by molecular systems that has much in common with the Franck-Condon theory describing the vibrational transitions in a molecule after absorption or emission of a photon. The principal elements are the quantum probabilities for the transitions between the energy levels of the studied system, which are induced by diffusion of a neutron. In this case, the fundamental concept of "energy landscapes", which was introduced by Hans Frauenfelder to describe the internal dynamics of proteins in terms of "jumps" between the minima of their (free) internal energy, can be integrated in the analysis of neutron scattering spectra by complex systems in general. The theory also provides an intuitive physical interpretation of Van Hove's correlation functions in the quantum regime, as well as their classical limit, which is usually considered in the analysis of quasi-elastic spectra of neutrons from proteins and other complex molecular systems.
The success of this method relies on the use of nonvolatile liquid matrices, which avoids the passage through the solid phase conventionally used in MALDI and the denaturation of the non-covalent assemblies. By their increased viscosity, these matrices also have the advantage of better mimicking the cluttered environments of living organisms.
The reliability of this method has been shown for non-covalent protein protein and ligand protein systems. This new approach could be used for screening of therapeutic protein ligands and facilitating the analysis of membrane protein complexes by mass spectrometry.
Rho-dependent termination is a specific bacterial mechanism, which plays a major role in gene expression and maintenance of genomic integrity. This is an important mechanism for the fast adaptation of bacteria to environmental changes or stresses. Although Rho-dependent termination sites are very diverse and without a real consensus sequence, CBM researchers have identified dozens of quantitative sequence descriptors (eg% C and% G) that, taken collectively, provide good prediction of the sites of Rho action in the model genomes of Escherichia coli and Salmonella (85% success rate).
This work was published in the journal Nucleic Acids Research.