Fish and wash some crystals then run them on a SDS-gel, then you will know for sure if it's protein or not.
Jürgen On Apr 18, 2010, at 10:46 PM, tat cheung cheng wrote: > Hi all, > > I have got some crystals, the purified protein was in Tris buffer with 300mM > NaCl for crystallization. they grew in light weight PEG, PEG400 or monomethyl > ethyl PEG500, they were needle shaped, could be long (~0.2mm) but very thin > all the time and sometimes grew into sea-urchin like needle cluster. > What interesting is, when i gridded crystallization conditions against pH or > PEG amount, the crystals sizes and shapes varied, and the crystals were > fragile so i believed they were protein crystals in nature. But upon X-ray > diffraction, they gave no reflection at all, not even a faint spot. > I wonder, beside silly mistakes like misalignment of the crystal to the beam, > not enough exposure time, what could be the reason for this mysterious > crystals? Are they protein or PEG or what? > Thanks very much. > > Tc > > > > - Jürgen Bosch Johns Hopkins Bloomberg School of Public Health Department of Biochemistry & Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street, W8708 Baltimore, MD 21205 Phone: +1-410-614-4742 Lab: +1-410-614-4894 Fax: +1-410-955-3655 http://web.mac.com/bosch_lab/
