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

John Spence, Kevin Schmidt, J. S. Wu, G. Hembree, Uwe Weierstall, B. Doak, Petra Fromme

Research output: Contribution to journalArticlepeer-review

50 Scopus citations


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 (US)
Pages (from-to)237-245
Number of pages9
JournalActa Crystallographica Section A: Foundations of Crystallography
Issue number2
StatePublished - Mar 1 2005

ASJC Scopus subject areas

  • Structural Biology


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