Re: [ccp4bb] Missing DNA density in Protein DNA complex structure

2013-05-05 Thread Paul Paukstelis
How is the DNA packed in the crystal? Coaxially stacked pseudo-infinite helices? --paul On 05/05/2013 02:21 AM, ASHOK KUMAR Patel wrote: Hi all, I am working on a DNA binding protein (mol wt around 30 kDa), which binds to Duplex DNA in a non-specific sequence manner. The structure has been

Re: [ccp4bb] Missing DNA density in Protein DNA complex structure

2013-05-05 Thread Raji Edayathumangalam
Dear Ashok, There are many questions underlying your questions. A couple of things to check right off the bat: (1) Do you actually know that your crystal still contains all of the DNA bp that you started with? Did you analyze the contents of your crystal by native PAGE, mass spec or other methods

Re: [ccp4bb] Missing DNA density in Protein DNA complex structure

2013-05-05 Thread Phoebe A. Rice
Because your protein binds non-specifically, it could be an interesting case of static disorder where the DNAs are making a pseudo-continuous helix through the crystal regardless of sequence, and 12 bp/turn happens to fit nicely into a generic lattice. How does the density for the individual bas

Re: [ccp4bb] Missing DNA density in Protein DNA complex structure

2013-05-05 Thread Opher Gileadi
Hi Ashok, You say your DNA is palindromic - have you looked at the possibility that the longer DNAs are actually folded on themselves rather than duplexes of two separete oligos? Depending on the location of the centre of your palindrome and on interactions with adjacent molecules, this could

[ccp4bb] off topic question regarding SPR

2013-05-05 Thread Faisal Tarique
Dear all i have a basic question regarding SPR experiment and that is: What is the recommended glycerol concentration in the protein sample for doing SPR experiment and getting the best possible result.? i have kept 10% Glycerol in my protein preparation..is it O.K ? Thanx in advance -- Regards

Re: [ccp4bb] off topic question regarding SPR

2013-05-05 Thread Bosch, Juergen
Hi Faisal, whatever makes your protein happy is good. What type of experiment were you thinking of ? Protein-protein interaction or protein-small molecule interaction ? In the latter case add some Tween20 or Brij-35 into the mix. A decent overview can be found under this webpage for what to con