Re: [ccp4bb] decrease of background with distance?

The source for the X-ray background are points along the air path post-collimator including the sample with loop and cryoprotecdant (or capillary and mother liquor). So the 1/r^2 falloff is noticable going from 100 mm to 200 mm. The same counts in a 2x2 pixel area is now seen in a 4x4 pixel

[ccp4bb] Methylation of macromolecular complexes

Hi all, I have a question regarding the methylation of macromolecular complexes. Is there any report where a macromolecular complex has been successfully methylated and later on crystallized. Is methylation a method of choice to chemically modify macromolecular complexes where the entropical

Re: [ccp4bb] decrease of background with distance?

Jim's point is well taken and can perhaps be generalised to say one is limited either by the crystal or by the set up for recording the diffraction. To optimise things it is useful to know where the limits are. With some tightly focused synchrotron beams you can also see your spots getting

Re: [ccp4bb] Methylation of macromolecular complexes

Jan Rash wrote: Hi all, I have a question regarding the methylation of macromolecular complexes. Is there any report where a macromolecular complex has been successfully methylated and later on crystallized. Is methylation a method of choice to chemically modify macromolecular complexes

[ccp4bb] AW: [ccp4bb] Methylation of macromolecular complexes

Hi Jan, Maybe this link http://www.jenabioscience.com/cms/en/1/catalog/529_jbs_methylation_kit.html http://www.jenabioscience.com/cms/en/1/catalog/529_jbs_methylation_kit.html or these references helps… References [1] Kim et al. (2008) Large-scale evaluation of protein reductive

[ccp4bb] Age Concern edition of the Computing Commission and Teaching Commission newsletter

Posted on behalf of Lachlan Cranswick: The Computing Commission and Teaching Commission has produced a joint November 2009 newsletter on the theme of Age Concern, which deals with issue concerning the slow march towards retirement of the major generation of crystallographic programmers, as

Re: [ccp4bb] Methylation of macromolecular complexes

Hi all, I have a small complex, one component is 13 kDa with structure available and the other is 7 kDa, which could not be able to grew crystals after lots of efforts. It grew crystals after methylation and diffracted to 2.3 A, however, I could not be able to solve the structure using

Re: [ccp4bb] Methylation of macromolecular complexes

Hi Peter, How do you know you have crystallized the complex? Perhaps MR is not working because your crystals only contain the small protein. good luck, Eric  Hi all,   I have a small complex, one component is 13 kDa with structure available and the other is 7 kDa, which could not be able

Re: [ccp4bb] Methylation of macromolecular complexes

I have a small complex, one component is 13 kDa with structure available and the other is 7 kDa, which could not be able to grew crystals after lots of efforts. It grew crystals after methylation and diffracted to 2.3 A, however, I could not be able to solve the structure using the structure of

[ccp4bb] Help request: Failed MR using the same molecule as model

Dear CCP4 community: I am a beginner to crystallography and therefore my apologies if this question is too simple. Basically we obtained several crystal forms of the same molecule, which is a hetero- trimer containing protein A(18kD), protein B(16kD) and a RNA segment(40nt or about 15kD).

Re: [ccp4bb] Methylation of macromolecular complexes

There is a reasonable experiment you can do: Take the unit cell of your (presumed) crystal complex and put the search model into the until cell in a way that seems reasonable (use coot, or your favorite program). Make structure factors (with CCP4 or your favorite program) and throw away the

[ccp4bb] Help request: Failed MR using the same molecule as model

Dear CCP4 community: Sorry if there is a duplicate post. I am a beginner to crystallography and therefore my apologies if this question is too simple. Basically we obtained several crystal forms of the same molecule, which is a hetero- trimer containing protein A(18kD), protein B(16kD) and a

Re: [ccp4bb] Methylation of macromolecular complexes

Yes, I’ve methylated a ~300 kDa complex once, just for kicks – and it still functioned. MS was fairly good as well, showing that essentially all accessible amines were altered. Notably I did not get the entire 300 kDa complex on MS – it did not survive TFA/Acetonitrile and I saw components

Re: [ccp4bb] Help request: Failed MR using the same molecule as model

Hi there, 2 things: Are you sure that the relative orientations of your components are the same in the different crystal forms? If you haven't done it already, it would be worth while trying to search for the individual components as well (could be difficult because your components are not so

[ccp4bb] MSD PISA

Hi All, I am using MSD PISA web server to analyze the protein ligand interface in my newly solved structure. The ligand in the structure is a new inhibitor (generated using PRODRG), so there is no entry for the inhibitor in the PDB. Therefore when I am uploading my pdb file to PISA server it is

Re: [ccp4bb] MSD PISA

Hi Koustav, I had the same question before and here is the answer from Eugene Krissinel, the developer of PISA: Yes PISA has a database of compounds, which contains certain interaction parameters. If a compound is not found in the database, then PISA does not know how it interacts with other