DIRECT PHASING OF ONE-WAVELENGTH ANOMALOUS SCATTERING DATA

Quan Hao¹, Ian Harvey^1,2, Elizabeth M. H. Duke², W. John Ingledew³ and S. Samar Hasnain^1,2

¹Faculty of Applied Sciences, De Montfort University, The Gateway, Leicester, LE1 9BH, U.K.
²CLRC Daresbury Laboratory, Warrington, WA4 4AD, U.K.
³School of Biomedical Sciences, St. Andrews University, St. Andrews, Fife, KY16 9TS U.K.

The structure of rusticyanin, an acid stable copper protein, has been determined at 2.1Å resolution by direct methods using the single wavelength anomalous scattering (SAS) of copper (f'' =3.9e^-). This is the largest unknown protein structure (MW ~16.8kDa) to be determined using the direct methods approach and it has been demonstrated that by exploiting the anomalous signal at a single wavelength, direct methods can be used to determine phases at typical (~2Å) macromolecular crystallographic resolutions.