Electron magnetic resonance in molecular biophysics: new and old looks to new and old problems

Abstract

The understanding the triad structure-dynamics-function leads to the most detailed description of processes involving biological molecules, in particular proteins. In this research proposal, we aim at using a combination of more traditional with more modern methods of Electron Magnetic Resonance (EMR), towards the determination of distance constraints and the detection of coexistence of molecular conformations, to investigate more traditional (such as peptide/membrane interactions) as well as more recent (such as intrinsically disordered proteins) problems in Molecular Biophysics. To do so, this proposal is divided in two problems: (I) the molecular interactions taking place in the functional mechanism of proteins and (II) fusion peptides from the glycoprotein S of SARS-CoV and their interactions with model membranes. In Problem I, we are interested in the human calcium binding protein S100A12 and in the Golgi Reassembly and Stacking Proteins (GRASPs). The first one is a more traditional problem (od problem) of searching for protein conformational changes in the presence of ligands (in this case, divalent ions), but exploited by using simulations of the EMR spectra and distance measurements (old and new looks). The second case is a new problem involving GRASP proteins that have shown features related to structural intrinsic disorder, a theme of research that has been expanding vigorously over the last years. GRASPs will be investigated by using the traditional look of CW-EMR combined with several other biophysical tools, and with potential for distance measurements through pulsed EMR. In Problem II, we are interested in the interactions between model membranes and low molecular mass ligands, such as biologically active peptides, drugs and metal complexes with antitumor activity. In this case, EMR will be jointly used, when necessary, with other methods, such as calorimetry, circular dichroism (CD) and fluorescence. This part of the project encompasses more traditional looks (spectroscopies in general) to more traditional problems, but with the addition of one new look, which is the use of pulsed EMR for distance measurements. The expected contributions are related not only to the specific issues of the problems, but also to the consolidation, in our state, of modern EMR methods, such as site directed spin labeling and distance measurements using double electron-electron resonance. (AU)