Hello Jacob, Quoting you, "Please let me know if you have a case where detwinning saved the day".
Well you asked for it so here is one example where twinning saved the day: "Crystal structure of pb9..." by Flayhan et al. (2014), J. Virol. 88 (2), 820-828. Without detwinning I think there would have been no crystal structure in the end... Cheers, Fred. From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Keller, Jacob Sent: Tuesday, October 11, 2016 2:15 AM To: [email protected] Subject: [ccp4bb] Why Does Detwinning Not Work? Dear Crystallographers, Based on some data sets I have looked at and anecdotal-type evidence here and there I have gotten the impression that detwinning does not help in structure solution. (Please let me know if you have a case where detwinning saved the day.) Is there a clear answer to this enigma anywhere, to anyone's knowledge? Wouldn't it seem that *any* detwinning would be better than *no* detwinning? I understand that the errors explode as one approaches 50% twins and does detwinning, but still, I don't think one *loses* information by detwinning, right? Take the case of a 33% twin: since the twin-reflections are on average about half the intensity of the non-twin, and since they are generally not correlated in intensity, isn't this like having noise added at 50% of the measured intensity? So why does detwinning make things worse generally? Is there something wrong in the assumptions underlying the detwinning algorithm, or perhaps something about the calculation that throws things off? A related sub-enigma: why is MR generally immune to twinning, but anomalous methods are susceptible? All the best, Jacob Keller ******************************************* Jacob Pearson Keller, PhD Research Scientist HHMI Janelia Research Campus / Looger lab Phone: (571)209-4000 x3159 Email: [email protected]<mailto:[email protected]> ******************************************* ----- Upozornení: Není-li v této zpráve výslovne uvedeno jinak, má tato E-mailová zpráva nebo její prílohy pouze informativní charakter. Tato zpráva ani její prílohy v zádném ohledu Biotechnologický ústav AV CR, v. v. i. k nicemu nezavazují. Text této zprávy nebo jejích príloh není návrhem na uzavrení smlouvy, ani prijetím prípadného návrhu na uzavrení smlouvy, ani jiným právním jednáním smerujícím k uzavrení jakékoliv smlouvy a nezakládá predsmluvní odpovednost Biotechnologického ústavu AV CR, v. v. i. Disclaimer: If not expressly stated otherwise, this e-mail message (including any attached files) is intended purely for informational purposes and does not represent a binding agreement on the part of Institute of Biotechnology CAS. The text of this message and its attachments cannot be considered as a proposal to conclude a contract, nor the acceptance of a proposal to conclude a contract, nor any other legal act leading to concluding any contract; nor does it create any pre-contractual liability on the part of Institute of Biotechnology CAS
