Ta-Q-Bin

Multi-crystal native SAD analysis at 6 keV

“…Thus, the f 00 of sulfur increases by 36%, from 0.70 to 0.95 electrons, when the energy is reduced from 7.1 to 6.0 keV. The adverse effects of air scattering and absorption are largely eliminated by using a helium beam path, and our calculations show that the effects of sample absorption are readily addressed by using appropriately smaller crystals (Liu et al, 2013). With such attention to experimental conditions, the previously suggested X-ray energy of 6 keV ( = 2.1 Å ; Mueller-Dieckmann et al, 2005) may be routinely suitable for multi-crystal native SAD phasing.…”

“…A further advance has come with procedures for enhancing the signal-to-noise ratios for anomalous diffraction signals by incorporating data from multiple crystals (Liu et al, 2011). The more recent extension of such multi-crystal procedures to measurements at 7 keV, where light-atom anomalous diffraction signals are increased, has led to routine and robust de novo structure determination of native SAD structures (Liu et al, 2012(Liu et al, , 2013. Real-life applications have been made in determining various structures at resolutions between 2.3 and 2.8 Å with unique protein sizes of between 144 and 1200 amino-acid residues.…”

“…In comparison to heavier atom SAD phasing, native SAD phasing requires measurements at energy lower than 9 keV to realise appreciable anomalous signals. Complications such as air scattering, absorption, sample size, radiation damage and detector geometry may arise when performing experiments at lower energy (Liu et al, 2013;Weiss et al, 2001Weiss et al, , 2005. As a compromise to mitigate such effects, we have limited our previous native SAD phasing to 7.1 keV (the Fe K edge).…”

Bayesian machine learning improves single-wavelength anomalous diffraction phasing

“…This led to the development of the inverse-beam geometry (IBG) method (Hendrickson et al, 1985;Dauter, 1997;Rice et al, 2000). According to de Sanctis et al (2016), a systematic study on the beneficial use of IBG is not available, but there are numerous reports where IBG was used successfully (Liu et al, 2012(Liu et al, , 2013Akey et al, 2014;Jungnickel et al, 2018;Noble et al, 2018;Rozov et al, 2019). An alternative strategy focuses on increasing the occurrence of Bijvoet's pairs on the same diffraction image and thereby minimizing the effect of radiation damage difference and the effect of other time-dependent systematic errors between them (Dauter, 1999).…”

Facilitating best practices in collecting anomalous scattering data forde novostructure solution at the ESRF Structural Biology Beamlines

“…The two data sets sets are processed separately and then scaled together to provide the final data set. Although, to our knowledge a systematic study on the beneficial use of inverse-beam geometry is not available, many examples of successful phasing experiments using this technique have been reported in the literature (Liu et al, 2012(Liu et al, , 2013Akey et al, 2014).…”