Direct-method SAD phasing of proteins enhanced by the use of intrinsic bimodal phase distributions in the subsequent phase-improvement process

✍ Scribed by Wu, Li-Jie ;Zhang, Tao ;Gu, Yuan-Xin ;Zheng, Chao-De ;Fan, Hai-Fu

• Book ID: 104478499
• Publisher: International Union of Crystallography
• Year: 2009
• Tongue: English
• Weight: 75 KB
• Volume: 65
• Category: Article
• ISSN: 0907-4449
• DOI: 10.1107/s0907444909037044

✦ Synopsis

A modified SAD (single-wavelength anomalous diffraction) phasing algorithm has been introduced in the latest version of the program OASIS. In addition to direct-method phases and figures of merit, Hendrickson-Lattman coefficients that correspond to the original unresolved bimodal phase distributions are also output and used in subsequent phase-improvement procedures in combination with the improved phases. This provides the possibility of rebreaking the SAD phase ambiguity using the ever-improving phases resulting from the phase-improvement process. Tests using experimental SAD data from six known proteins showed that in all cases the new treatment produced significant improved results.