Structural Dependence of Nuclear Magnetic Resonance Chemical Shift Anisotropy in Proteins by Quantum Chemical Simulations

Recent advances in nuclear magnetic resonance (NMR) spectroscopy, in particular methods based on transverse relaxation optimized spectroscopy (TROSY) allow to determine the chemical shift anisotropy (CSA) of specific atoms in solution, that was before possible in the solid-state NMR spectroscopy of crystalline and powder samples only. The conformational dependence of CSA is of great theoretical and practical interest both as a source of geometry information by itself and also as a parameter givin rise to an interference with other relaxation terms (e.g. dipolar and Curie spin relaxation). In the proposed research project quantum chemical methods at density functional theory level will be used to calculate CSA tensors for backbone atoms in oligopeptides for different conformations and hydrogen bond geometries. The results should allow the prediction of CSA tensors for different conformations, their sensitivity of various changes in molecular geometry and consequential assess the relevance of CSA tensors determination for structural studies in peptides and proteins. Thus CSA values could become important a new parameters for application in protein secondary structure recognition, increasing at the same time the number of sources for protein geometry constraints.