Hi Folks, Zinc is also ubiquitous in many of the plastics and reagents we use. Many years ago we used anomalous diffraction to analyse a protein known to bind nickel or zinc. We did one measurement on fresh crystals and clearly identified nickel. A few months later when we had more beamtime we repeated the experiment to get better data, on crystals from the same tray, and the nickel had transmuted into zinc. Zinc had not been added on purpose at any point. Cheers, Charlie
-- Charlie Bond – http://bondxray.org<http://bondxray.org/>/ School of Molecular Sciences https://www.uwa.edu.au/science/home/schools/school-of-molecular-sciences The University of Western Australia +61 8 6488 1191 - 4.32 Bayliss Building To make an appointment, please contact [email protected] From: CCP4 bulletin board <[email protected]> on behalf of Guenter Fritz <[email protected]> Reply-To: Guenter Fritz <[email protected]> Date: Wednesday, 22 January 2020 at 2:06 am To: "[email protected]" <[email protected]> Subject: Re: [ccp4bb] Unusual monomer-monomer interface in crystal Dear Chris, are there any metal ions in your buffer or in your protein. We had a similar looking case. A Zn2+ ion bridged two monomers. Our protein is a Zn2+ binding protein. The Zn2+ originated from some denatured protein in the drop. No extra Zn2+ was in the crystallization buffer. http://www.rcsb.org/structure/5CHT<https://aus01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.rcsb.org%2Fstructure%2F5CHT&data=02%7C01%7Ccharles.bond%40uwa.edu.au%7Ca34debdf669f49a5ffca08d79e9c9ec1%7C05894af0cb2846d8871674cdb46e2226%7C1%7C1%7C637152267821601257&sdata=mOXXgqkoQCvePW58qRd4elEFNifEJDHC6W%2BYBbUbTX8%3D&reserved=0> https://www.nature.com/articles/nsmb.3371<https://aus01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.nature.com%2Farticles%2Fnsmb.3371&data=02%7C01%7Ccharles.bond%40uwa.edu.au%7Ca34debdf669f49a5ffca08d79e9c9ec1%7C05894af0cb2846d8871674cdb46e2226%7C1%7C1%7C637152267821601257&sdata=6VvzhJS%2BpuWzpD1rVkgh%2FkatkQXIJAdvVwRrgmSDmU4%3D&reserved=0> HTH Guenter Dear CCP4BB Users, I've recently solved the ~2.2 angstrom structure of a protein. In my electron density there are unusual monomer-monomer interfaces involving pairs of His and Cys residues (see https://ibb.co/wdWBcdk<https://aus01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fibb.co%2FwdWBcdk&data=02%7C01%7Ccharles.bond%40uwa.edu.au%7Ca34debdf669f49a5ffca08d79e9c9ec1%7C05894af0cb2846d8871674cdb46e2226%7C1%7C1%7C637152267821611256&sdata=FSQTyxD%2FhD0JqP7KjLWEW2LSkVhNCGj%2BzI1rryxorNU%3D&reserved=0>). Note the positive Fo-Fc density between the four side chains. As there is not adequate space for a water molecule or metal ion, perhaps the Cys residues are partially tied up disulfide bonds? However, the protein looks to be fully monomeric based on LC-MS measurements. Has anyone else observed crystal-driven formation of disulfide bridges? Aside from this region, there is no extensive interface between momoners, and PDBePISA suggests a monomeric state. Thanks in advance for any advice! Best wishes, Chris ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1<https://aus01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jiscmail.ac.uk%2Fcgi-bin%2Fwebadmin%3FSUBED1%3DCCP4BB%26A%3D1&data=02%7C01%7Ccharles.bond%40uwa.edu.au%7Ca34debdf669f49a5ffca08d79e9c9ec1%7C05894af0cb2846d8871674cdb46e2226%7C1%7C1%7C637152267821611256&sdata=QGZ09tqtvks3E%2F3YVEdYlzNPllOgY%2BvOvJAZ2XWSfdw%3D&reserved=0> ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1<https://aus01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jiscmail.ac.uk%2Fcgi-bin%2Fwebadmin%3FSUBED1%3DCCP4BB%26A%3D1&data=02%7C01%7Ccharles.bond%40uwa.edu.au%7Ca34debdf669f49a5ffca08d79e9c9ec1%7C05894af0cb2846d8871674cdb46e2226%7C1%7C1%7C637152267821621247&sdata=FwgE7caOHv5NZFLKsRGT6t0sVnT0VfHSpxoI42eTGDE%3D&reserved=0> ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
