Dear Mark, I did think it was salt, so I checked the same batch of protein which went for crystallization by running a gel, it was intact, no cleavage. My doubts arose because of two things
1. I crystallized the same protein with another ligand, in very similar condition (10% PEG3350, 50mM Zn acetate, 0.25M Sod citrate) which diffracted and ligand density was visible in the protein structure 2. When can salt crystals give closely spaced spots which is seen in the image that was attached Thank you Regards Kavya On 2023-02-03 16:50, Mark J. van Raaij wrote: > like others mentioned, looks like something in between a salt and a protein, > perhaps TCEP, the ligand, a peptide cleaved from your protein by trace > protease. > If possible, I would move the detector closer, collect an atomic resolution > dataset and try to solve the structure by direct methods. You never know, it > could be something interesting. > > Mark J van Raaij > Dpto de Estructura de Macromoleculas, lab 20B > Centro Nacional de Biotecnologia - CSIC > calle Darwin 3 > E-28049 Madrid, Spain > tel. +34 91 585 4616 (internal 432092) > Section Editor Acta Crystallographica F > https://journals.iucr.org/f/ > https://namedrop.io/markvanraaij > >> On 3 Feb 2023, at 09:22, kavyashreem <[email protected]> wrote: >> >> Dear all, >> >> We crystallized a protein (30kDa) + ligand (by cocrystallization), in the >> condition 10%PEG3350, 50mM Zinc acetate. >> >> Protein was in the buffer 20mM HEPES, 150mM NaCl, 1uM ZnCl2, 4mM TCEP, pH 8. >> >> >> Crystal: Crystal: >> crystal under UV m >> >> <b06fc576.png> <e091c7fd.png> <8ef9453e.png> >> >> When we collected the data at an in-house facility, it looked something like >> this: >> >> <b903961d.png> >> >> The minimum resolution spot is around 9Ang and maximum ~2.2Ang. >> >> I have not come across a protein diffraction like this, nor of a salt. When >> I ran the gel for the incubated protein (protein+ligand), there was no >> degradation. >> >> Although, I was sure there is some problem with this image I tried >> processing, which could not be, But indexing showed a unit cell of 11Ang, >> 11Ang, 46Ang in P3. which was quite expected for two of the axes but not the >> third. >> >> Can anyone please shed some light on this diffraction image? >> >> How can it happen? >> >> Thank you >> >> Regards >> >> Kavya >> >> ------------------------- >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 ######################################################################## 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/
