Dear ccp4 Users, I would like to say thank you to all of your valuable advices to optimize the needle crystal and related problems when dealing with membrane protein. Here I report the summary of your advices to help other students who got the same problem:
1. Additive screening from Hampton Research maybe useful in some cases. 2. Can apply techniques/tricks that are used for soluble proteins, such as vary Mg2+ salt conc and identity, temperature, volume/reservoir ratio, protein conc. and even trying different detergents and/or mixtures including DDM 3. Round shape crystal is maybe detergent crystal, but other opinion shows that DDM cannot create crystal in aqueous solution. I am still confused about this problem but it's hard to optimize these kind of crystal. 4. Try to collect data on the micro-diffraction beamline (but the facilities is only available in US and Europe). 5. Powder diffraction also can be used to check the protein crystal or detergent crystal and even solve the structure. Thank you very much for your advices and suggestion! My best regards, TriNgo PhD Student- Sungkyunkwan University, Korea
