Dear Marina, A lot can happen with twinning andthe crystallization process does not always adhere to rules written in text books. The first thing I would do is to look at the predicted spots to see if the "split" spots are predicted as single spots (and would then really be split), or if they are predicted as two different spots (and would therefore not be split). I assume that the cell dimensions of the P622 and P3(2)21 cell are the same (no doubling of some sell axis) and that the detection of twinning was based on the intensity distribution of the data set. What may have happened is that if the transition between the two twin domains is not perfect, the two twin domains may have slightly different orientations, leading to split spots.
My 2 cents, Herman -----Ursprüngliche Nachricht----- Von: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> Im Auftrag von Marina Gárdonyi Gesendet: Freitag, 12. März 2021 11:31 An: CCP4BB@JISCMAIL.AC.UK Betreff: [ccp4bb] Can twinning be seen in the diffraction pattern? 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 https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.agklebe.de%2F&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=lcvs%2Fk2xR0IsD0jw4VTEU25lfReTwByxq9ci%2F%2Bn9b1U%3D&reserved=0 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jiscmail.ac.uk%2Fcgi-bin%2FWA-JISC.exe%3FSUBED1%3DCCP4BB%26A%3D1&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=A%2F9uSyur0W1vC%2BsKwSQtMVwo145vctPNXkXjQrrQPBo%3D&reserved=0 This message was issued to members of https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.jiscmail.ac.uk%2FCCP4BB&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=Qied8%2BDj6d46h1p8Y%2BNK%2F7gIIv9iDxT2%2Fjd3dM7llQE%3D&reserved=0, a mailing list hosted by https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.jiscmail.ac.uk%2F&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=uRUeCZQHZlWS0iGJrBYSmyulHDMHayMsb1wCxcYeuwA%3D&reserved=0, terms & conditions are available at https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jiscmail.ac.uk%2Fpolicyandsecurity%2F&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=AFsBVc5LtTklf4gzMCItFESgyTCuwqLLZk77ypDYEcE%3D&reserved=0 ######################################################################## 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/
