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, bigger crystals in the same condition is to set up bigger drops and dilute the well solution by water to 95%, 90%, 85%... And if that doesn't work, you can try additive screen on this current crystallization condition.
As a control for determining if these are complex crystals or just DNA crystals, you can set up a crystallization in the same crystallization condition with just DNA, no protein. -Gyan On Mon, Jun 19, 2017 at 9:20 AM, Joseph Ho <sbddintai...@gmail.com> wrote: > 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 the picture of crystals are attached. In this > particular condition, it is 30%PEG3350, sodium succinate pH5.5 and > 100mM NaCl. The crystal seems floating and sit in the bottom. We do > some test shot from other conditions and it is not salt crystals. The > crystals can suck in izit dye. I do some google and it seems izit dye > also turns dsDNA crystal into blue. We also do UV/Vis microscope but > no Trp fluorescence (6 Trp in 256 aa). It may due to low Trp. > > This is our first time to work on protein/DNA complex crystals and we > are not certain if this is just DNA or protein/DNA crystals. Can you > provide your comments on our hits? > > Thank you for your help > > Joseph > -- Gyanendra Kumar, PhD Associate Scientist, St. Jude Children's Research Hospital, Department of Structural Biology, 262, Danny Thomas Place, MS-311 Memphis, TN 38105 Cell: 631-875-9189 https://www.linkedin.com/in/gyanendrakumar https://scholar.google.com/gyanendrakumar <https://scholar.google.com/citations?user=lnil0IQAAAAJ&hl=en> https://www.researchgate.net/profile/Gyanendra_Kumar3 http://stjude.academia.edu/GyanendraKumar -------------------------------------------------------
