Hi Rui,
In addition to what Fred has advised, you could also try varying other parameters like temperature and protein concentration. 32 % is a very high concentration of precipitant. Maybe you could try using a bigger PEG (like PEG 8000), at a lower concentration. It worked for me once. Also, if ever you are at ESRF, you could try the crystal dehydrating device. Ganesh ********************************************** The boast of heraldry, the pomp of power, And all that beauty, all that wealth e'er gave, Awaits alike the inevitable hour. The paths of glory lead but to the grave. -Thomas Gray, Elegy Written in a Country Churchyard ********************************************** On Thu, 4 Feb 2010 23:39:14 -0500, rui wrote: Hi, All, We are trying to crystallize a protein and found some initial hit in the following conditions, pH 4.8, 0.2 M AS or some other salts ( NaCl,LiCl, MgCl2 ), 32% PEG4000 or PEG3350 ). However the quality of the crystal is not so great,some of them look like needle cluster(very long in length), some of them look like multi-crystals or hollow inside. We tried to optimize the pH and PEG and tested one that diffracts at 2.9A. For the next, how to improve resolution?Any suggestions? Even mutate the protein to get a high resolution is ok, generally what kind of mutation would make proteins crystallize better? Thanks. --
