Ph,D., New York University, 1992
Phone: 718-951-5000 x1426
Nature of Research:
Infectious, transmissible spongiform encephalopathies (e.g., “Mad Cow Disease”) are a set of fatal, neurodegenerative diseases for which there is no cure. The infectious agent is a misfolded version of a normal, cellular protein called the prion protein. The mechanism of disease propagation appears to involve the catalyzed misfolding of the cellular, protease-sensitive prion conformer (PrPsen) by the misfolded, protease-resistant conformer (PrPres). The structural conversion results in a change of secondary structure from primarily α helix to β sheet, but the details of this misfolding process are not known. This project will identify the surface of the infectious prion protein that is available for the conformational conversion process, by exploiting the known adsorption of the infectious protein form to metal surfaces, and the capability of the adsorbed prion protein to affect the conformational conversion. (NB: This project will utilize mouse prion protein, which is noninfectious to humans.)
Methods
Study of the metal surface-bound mouse prion protein entails a complementary spectroscopic approach.
- Surface-enhanced Raman Spectroscopy selects for surface adsorbed residues only. Surface-enhanced Raman spectroscopy (SER) is a technique involving the surface adsorption of molecules to a nanoscaled, particulate metal surface. The interaction of light with the surface plasmons of the particulate metal results in a huge (ca. 106) amplification of the Raman signal from only the molecules that are within a very short distance of the surface. Thus, a specific subset of the protein – that which is in intimate contact with the metal surface – can be idenfified.
- RA-IR spectroscopy reveals global protein conformation. Analogously, reflective absorbance-infrared (RA-IR) spectroscopy probes proteins adsorbed to metal surfaces for their secondary structure. Thus, the RA-IR and SER techniques are complementary: the former provides a global picture of the adsorbed protein conformation while the latter provides close-up details of specific protein residues that are very close to the metal surface.
Rotational Proposal
In this rotation, a student will learn:
- Preparation of the nanoscale metal surface for protein adsorption
- Basics of Raman instrumentation, maintenance; data collection and analysis.
References
Flechsig, E., Hegyi, I., Enari, M., Schwarz, P., Collinge, J., and Weissmann, C. (2001). Transmission of Scrapie by Steel-Surface-Bound Prions. Molec Med 7, 679-684.
Kneipp, K., Kneipp, H., Itzkan, I., Dasari, R.R., Feld, M.S. (2002) Surface Enhanced Raman Scattering and Biophysics, Journal of Physics C14, R597 ff.