Diffraction and imaging from a beam of laser-aligned proteins: Resolution limits

J. C.H. Spence, K. Schmidt, J. S. Wu, G. Hembree, U. Weierstall, B. Doak, P. Fromme

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Abstract

The effect of the limited alignment of hydrated molecules is considered in a laser-aligned molecular beam, on diffraction patterns taken from the beam. Simulated patterns for a protein beam are inverted using the Fienup-Gerchberg-Saxton phasing algorithm, and the effect of limited alignment on the resolution of the resulting potential maps is studied. For a typical protein molecule (lysozyme) with anisotropic polarizability, it is found that up to 1 kW of continuous-wave near-infrared laser power (depending on dielectric constant), together with cooling to liquid-nitrogen temperatures, may be needed to produce sufficiently accurate alignment for direct observation of the secondary structure of proteins in the reconstructed potential or charge-density map. For a typical virus (TMV), a 50 W continuous-wave laser is adequate for subnanometre resolution at room temperature. The dependence of resolution on laser power, temperature, molecular size, shape and dielectric constant is analyzed.

Original languageEnglish
Pages (from-to)237-245
Number of pages9
JournalActa Crystallographica Section A: Foundations of Crystallography
Volume61
Issue number2
DOIs
Publication statusPublished - Mar 1 2005

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ASJC Scopus subject areas

  • Structural Biology

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