Re: [ccp4bb] Protein or DNA crystals

2017-06-21 Thread Patrick Shaw Stewart
We have sometimes used Michael Garavito's excellent suggestion of diffusing glutaraldehyde into the drops - mentioned on this board a few days ago. Our protein crystals either turned brown or turned into brown goo. Michael and others, what effect would you expect glutaraldehyde to have on DNA

Re: [ccp4bb] Protein or DNA crystals

2017-06-20 Thread Diana Tomchick
It’s been my experience that protein crystals with that high a percentage of tryptophan residues (>2%) should give a very clearly positive result from a UV microscope such as a Jansi UVEX. Diana ** Diana R. Tomchick Professor Departments of

Re: [ccp4bb] Protein or DNA crystals

2017-06-20 Thread Phoebe A. Rice
o pr...@uchicago.edu From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] on behalf of Joseph Ho [sbddintai...@gmail.com] Sent: Monday, June 19, 2017 9:20 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Protein or DNA crystals Dear all: I would like to seek

Re: [ccp4bb] Protein or DNA crystals

2017-06-19 Thread CHAVAS Leonard
Dear Kumar you said 'shot from other conditions': we do not know then if you shot these crystals or not. Else: - DNA should give you an X pattern, most of the time. - protein should give you at least low resolution pattern, or faint rings if it is powder pattern like - salt should give you

Re: [ccp4bb] Protein or DNA crystals

2017-06-19 Thread Gyanendra Kumar
Hi Joseph, Are you having trouble getting bigger crystals. You said you shot them, and they are not salt. Do they diffract at all? If they are diffracting to any extent, you could optimize the crystallization condition to get better, bigger crystals and shoot them. A simple way of growing fewer,

Re: [ccp4bb] Protein or DNA crystals

2017-06-19 Thread V Nagarajan
Hi Joseph, Could you post the UV fluorescence image? Oftentimes, UV absorbing objects that do not fluoresce (such as nucleic acid crystals) show up dark against a brighter background in UV fluorescence. V. Nagarajan JANSi On 6/19/2017 7:20 AM, Joseph Ho wrote: Dear all: I would like to

Re: [ccp4bb] Protein or DNA crystals

2017-06-19 Thread Nicolas FOOS
Dear Joseph, I think, you already did the most classical test to determine what is in your crystal. Maybe you can try a destructive approach by washing the crystal prior to put them in Agarose gel do a short run and color with ethydium bromide. Simpler, you can also melt the crystal after

[ccp4bb] Protein or DNA crystals

2017-06-19 Thread Joseph Ho
Dear all: I would like to seek your opinion on our crystal hits. We are working on protein/dsDNA complex. By changing different protein and DNA (14-22bp) constructs, we recently got some hits from commercial screens using sitting drop vapor diffusion (very small xtals). The precipitant is PEG and