Marvin D. Kemple Ph.D.Professor, Emeritus, Department of Physics
- 1971 Ph.D. Physics, University of Illinois, Urbana, IL.
- 1965 M.S. Physics, University of Illinois, Urbana, IL.
- 1964 B.S. Physics, Purdue University, West Lafayette, IN.
Our research interests center on utilizing and further developing magnetic resonance techniques for probing the dynamics and the conformation of macromolecules in liquid solutions. In recent years there has been a flurry of activity in the application of the basic laws of physics to simulate protein dynamics. However, experimental verification of the results of those simulations is quite limited largely because the simulations are restricted to motions on the subnanosecond (<10-9s) time scale due to the sheer size of the computations involved. We are attempting to rectify the lack of experimental evidence for the computer results by taking advantage of nuclear magnetic resonance (NMR) relaxation and fluorescence anisotropy methodologies to monitor internal rotational motion in peptides and proteins. The basis of the approach adopted is first to measure various NMR relaxation properties of 13C- and 15N-labeled fluorescent and non-fluorescent amino acids, which are incorporated synthetically and biosynthetically into peptides and proteins, and then to compare the motional information found by NMR with that found from fluorescence measurements on the same samples. Using two quite distinct techniques affords us the opportunity to mutually validate the inferences drawn from the measurements. Computer simulations of the dynamics and graphics depictions of the molecules are carried out in tandem with the experiments. The long-term aim of our work is an enhanced understanding of the determinants of internal motion in proteins.
Several approaches are being used to probe peptide and protein structure in liquids. 13C and 15N chemical shift values are sensitive to secondary structure in a reproducible fashion, and therefore relatively simple spectral measurements can be exploited to deduce site-specific molecular conformation. In addition intramolecular distances can be measured directly from sophisticated multi-dimensional NMR spectra which make use of the interaction between the nuclear magnetic dipoles. The particular focus of our work is on establishing the reliability of the data interpretation and on searching for correlations between protein structure and function.
Publications & Professional Activities
Kemple MD and Vemuri G (2003) Noise Spectroscopy of Randomly Modulated Two-Level Systems, Recent Research Developments in Chemical Physics 4, 1-30.