Date : Wednesday, January 30, 2002
Time : 4:30 PM
Location: Willet Science Center Room 109
Professor Jeff Denny
Department of Mathematics
"PISEMA Powder Patterns and PISA Wheels"
Abstract: Solid-state NMR experiments have proven to be powerful tools for investigating structures of membrane proteins, which are difficult to study using solution NMR or x-ray crystallography. Resonance patterns observed in 2D solid-state PISEMA (polarization inversion spin exchange at magic angle) spectra have been shown to yield structural details of the protein. This talk presents a mathematical discussion of the PISEMA powder spectrum as the image in the frequency plane of a quadratic function from the sphere of unit vectors. Based on this analysis of powder patterns, a method will be discussed for solving systems of quadratic equations to determine possible structures of a protein. Parametric equations for PISA wheels will also be presented, which are specific patterns observed in PISEMA spectra of oriented peptides. These wheels are useful both in assigning resonances and in determining the orientation of a peptide with respect to the magnetic field.
Please join us for light refreshments at 4:15. We hope to see you there!