Hi Marina, The close-together spots in the zoom inset of your figure I think are not split spots, but separate reflections. They are close togeter because you appear to have a unit cell with one axis much longer than the other two (we work on elongated proteins, so we have some experience with that). The same short distances are also clearly visible in the picture on the bottom left. If you index the image in MOSFLM and it puts boxes around both I'd conclude they are separate reflections, but there are perhaps more sophisticated ways to verify this. So I think its true that in this case the twinning is not (obviously) visible in the diffraction pattern - but detected through intensity statistics later. Best wishes, Mark
Mark J van Raaij Dpto de Estructura de Macromoleculas Centro Nacional de Biotecnologia - CSIC calle Darwin 3 E-28049 Madrid, Spain > On 12 Mar 2021, at 11:30, Marina Gárdonyi > <marina....@pharmazie.uni-marburg.de> wrote: > > > Hello everyone, > > I am a PhD student at the Philipps-University in Marburg and I am currently > writing my thesis. > > I have problems to understand whether in my case twinning can be seen in the > diffraction pattern or not. > > I know that it depends on the type of twinning wheter you can see it in the > diffraction pattern. The crystal had a resolution of 2.2 A. During processing > it seemed to have the space group P622, but in the end it was P3(2)21. With > phenix Xtriage I found out, that the data set was twinned. The twin law was > -h,-k,l. So it should be merohedral twinning. > I read in a paper, that in case of merohedral twinning you cannot see it in > the diffraction pattern. But in my case that seemed not to be the case > because of splitted reflections. Or am I wrong??? > > I would be very happy to hear your opinion on that. Thanks in advance! > > Best regards, > Marina > > -- > Marina Gárdonyi > > PhD Student, Research Group Professor Dr. Klebe > > Department of Pharmaceutical Chemistry > > Philipps-University Marburg > > Marbacher Weg 6, 35032 Marburg, Germany > > Phone: +49 6421 28 21392 > > E-Mail: marina....@pharmazie.uni-marburg.de > > http://www.agklebe.de/ > > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing > list hosted by www.jiscmail.ac.uk, terms & conditions are available at > https://www.jiscmail.ac.uk/policyandsecurity/ > <diffraction-pattern.jpg><diffraction-pattern-2.jpg> ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
