AVS 52nd International Symposium
    Biomaterial Interfaces Friday Sessions
       Session BI+SS-FrM

Paper BI+SS-FrM2
Injection into Vacuum and Alignment of Biological Molecules for Electron Diffraction

Friday, November 4, 2005, 8:40 am, Room 311

Session: Biomaterials Surface Characterization
Presenter: D. Starodub, Arizona State University
Authors: D. Starodub, Arizona State University
R.B. Doak, Arizona State University
J.C.H. Spence, Arizona State University
U. Weierstall, Arizona State University
K. Schmidt, Arizona State University
G. Hembree, Arizona State University
Correspondent: Click to Email
Resolving the protein secondary structure (folding),critical for its functionality, is a demanding task, especially for the proteins, which cannot be easily crystallized. Recently it was proposed to collect diffraction patterns dynamically from an array of biological molecules embedded in submicron water droplets, consecutively traversing the intersection of a focused 50 keV electron beam and a polarized 100 W laser beam.@footnote 1@ The latter aligns the molecules due to field interaction with a dipole moment induced in the molecule with anisotropic polarizability tensor.@footnote2@ We show experimental results on generation of monodispersed microdroplets via growth of Rayleigh instability, their injection into high vacuum, evaporation and cooling. The limitations on the droplet size and temperature for a given jet source configuration are obtained. Rotational relaxation of the spherical (small protein) and rodlike (tobacco mosaic virus) biomolecules to thermal fluctuations about the equilibrium orientation is considered in viscous and free molecular flow regimes, and optimal conditions for alignment, sufficient to obtain sub-nanometer resolution in diffraction, are derived. We also consider adiabatic effects of different spatial profiles of laser beam intensity and droplet velocity on final oscillation states of a biomolecule. Supported by NSF funding SGER DBI-0429814. @FootnoteText@ @footnote1@J.C.H. Spence and R.B. Doak, Phys. Rev. Lett. 92, 198102(2004). @footnote2@J.C.H. Spence, K. Schmidt, J. Wu, G. Hembree, U. Weierstall, R.B. Doak, P. Fromme. Acta Cryst. A61, 237(2005).