Crambin: a direct solution for a 400-atom structure

• Published in: Acta crystallographica. Section D, Biological crystallography. Vol. 51; no. 1; pp. 33 - 38
• Main Authors: Weeks, C. M., Hauptman, H. A., Smith, G. D., Blessing, R. H., Teeter, M. M., Miller, R.
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01.01.1995
• ISSN: 1399-0047; 0907-4449; 1399-0047
• DOI: 10.1107/S090744499400925X

The crystal structure of crambin, a 46‐residue protein containing the equivalent of approximately 400 fully occupied non‐H‐atom positions, was originally solved at 1.5 Å by exploiting the anomalous scattering of its six S atoms at a single wavelength far removed from the absorption edge of sulfur. The crambin structure has now been resolved without the use of any anomalous‐dispersion measurements. The technique employed was an ab initio `shake‐and‐bake' method, consisting of a phase‐refinement procedure based on the minimal function alternated with Fourier refinement. This method has successfully yielded solutions for a smaller molecule (28 atoms) using 1.2 Å data, and a crambin solution was obtained at 1.1 Å.