Protein Crystallographic Methods

Combining Direct Methods with Single Isomorphous Replacement (SIR) or Single-wavelength Anomalous Diffraction (SAD) Data

2006 progress

Direct-method SAD phasing at lower resolutions down to 4Å .
Direct-method SIR phasing based on the partial model from SOLVE/RESOLVE
Fragment extension based on molecular replacemnt without SAD/SIR informatiom

1965 ~ 2005

Approach
Results
Publications

Background

        Solving a protein structure by using single isomorphous replacement (SIR) or one wavelength anomalous scattering (OAS) data is important when it is difficult to prepare multiple isomorphous derivatives and to collect multiwavelength anomalous diffraction data. However the phase ambiguity intrinsic in SIR or OAS data obstructs the use of them. The combination of direct methods with the SIR or the OAS technique may solve the problem and simplify the process of protein-structure analysis.
        MAD and MIR are two major methods of de novo solution of protein structures. The incorporation of direct methods with MAD or MIR phasing may lead to better results.