[PAST EVENT] Applied Science and Chemistry Seminar - Dr. Timothy Cross
Access & Features
- Open to the public
Title: Why Solid State NMR is Growing in Importance for Membrane Peptide and Protein Research
Abstract: Solid state NMR has a 35 year history in the field of membrane protein research. Uniquely structural, dynamic and functional characterizations can be made in a native-like liquid crystalline lipid bilayer. Such an environment confers a native-like structure and functional properties to the proteins that are often structurally and dynamically altered in lees native-like membrane mimetic environments. Here, I will use the M2 protein from Influenza A that has 4 known functions. In addition, several proteins from the Mycobacterium tuberculosis cell division apparatus, known as the divisome will be used to illustrate the capabilities of solid state NMR.
For decades solid state NMR has been known as a technology of low sensitivity ? indeed NMR, in general, is known for the large samples necessary to compensate for the low sensitivity of NMR experiments. Two factors are rapidly changing this view ? one is the use of 100 kHz magic angle sample spinning experiments that is fast enough to greatly reduce proton-proton couplings allowing for high sensitivity solid state NMR proton detection. I will borrow from other researchers some results on membrane proteins to show that structural biology can be performed on sub milligram quantities of protein. The second important feature is the advent of much higher magnetic fields that enhances both the spectral dispersion and the spectral resolution. As importantly, it allows for the expansion of the nuclei accessible by NMR to include many quadrupolar nuclei, such as 17O, 43Ca, 25Mg, 57Fe that traditionally give rise to very low sensitivity signals and very broad linewidths. Both of these features improve dramatically with higher fields which will be illustrated with a few spectra at 35.2 Tesla or 1.5 GHz for protons. Often biological NMR is thought of as a structural biology tool in competition with other structural biology methods, but for NMR, structure is just the start as the internal dynamics of the protein can be characterized and beyond that rates of chemical exchange relevant for understanding the functional mechanism and rates of reaction can be characterized leading to an understanding of functional biology.