Hi Parveen. DDM crystals can look a bit like that. Like a pencil that has been sharpened from both ends until there is very little pencil left, but often the ends are flatter than that. You can get tons of these (also with DM) in conditions with medium weight PEGs. Of course many proteins will also crystallize as hexagonal rods with PEGs :-) I'll take this chance to shre a thought with the community. When we say "contains x% of detergent y", are we sure of what there is in the protein stock? Most membrane protein stocks for crystallization will undergo a concentration step in a filter, and the membrane proteins themselves can be excellent detergent concentrators. For example, 0.05% DDM is about 1 mM DDM, hardly enough to make a belt around proteins that are 100 uM or higher. Do people measure how much detergent there really is in the final crystallization stock? It doesn't seem to get published, instead the concentration in the last purification step is often mentioned.
Jose. "Parveen Goyal" wrote: > Hi All, > > I got some hexagonal crystals in one of my crystal condition. The protein is > a membrane protein and contains 0.05% DDM. Has anybody seen DDM crysals and > if yes, how do they look like? > > thanks in advance > > Parveen Goyal > -- *************************** Jose Antonio Cuesta-Seijo Biophysical Chemistry Group Department of Chemistry University of Copenhagen Tlf: +45-35320261 Universitetsparken 5 DK-2100 Copenhagen, Denmark ***************************
