Dear Aleix, From what you say, it is also possible, that you see anomalous scattering of native elements present in your complex - your DNA contains P atoms, there might be also S in protein part and K+/Ca2+ in solvent. The signal is very weak at 12667 keV, but could give high anomalous correlation in lowest resolution shells.
What is the value of SigAno (column next to anomalous correlation) at 5.0 A resolution? What is the resolution of your complex (is 5 A close to diffraction limit or far)? Best, Filip From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of Aleix Tarrés Solé <atarre...@gmail.com> Reply-To: Aleix Tarrés Solé <atarre...@gmail.com> Date: Friday, 15 March 2019 at 22:17 To: "CCP4BB@JISCMAIL.AC.UK" <CCP4BB@JISCMAIL.AC.UK> Subject: [ccp4bb] Unknown anomalous scatterer Dear colleagues: Hereby, I would like to expose a problem I encountered during the data processing of one of my crystals. Recently I collected a full dataset of a native protein-DNA crystal at an energy of 12667KeV. To my surprise, after processing with XDS I can see that I have significant values of anomalous correlation up to 5 Angstrom resolution. Using the fluorescence scan on the beam, I could discard the presence of the following heavy atoms that could have ended up in my drop due to cross-contamination; Se, As, Fe, Zn and Pr. So far, my attempts to use this dataset for phasing have been sadly unsuccessful. I would like to know if somebody has experience in this kind of problem and can gently help with some advices. Thank you all in advance Aleix ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
