Dear Hay I suggest that you use analytical ultracentrifugation to determine the oligomeric state of the protein in solution. Mass spectrometry and light scattering are also useful, but there are so many examples of gel filtration proving erroneous it has questionable value as an analytical technique. For an example of a dimer interface predicted by PISA to be real you could look at Yoshida et al, JMB 423, 351 (2012). The protein is in fact a monomer in solution. PISA is a fantastic tool, but interfaces in crystals do not always reflect the solution state. My guess (with the information I have) is that your protein is probably a monomer too.
With regard to Michael Garavito's reply requesting more information, I would like to comment that scepticism is indeed an important god in the pantheon of science, but that that minor deity open-mindedness also deserves the occasional nod. 10-fold crystal symmetry is one example, but the list of "impossible" things now become mainstream is a long one (continental drift, Earth >100,000 years old, quantum mechanics....and so on). Bayes theorem cannot help you discover the truth if you have set its prior probability to zero. But I haven't my morning o-cha yet either. good luck Jeremy On Dec 11, 2014, at 9:27 PM, Hay Dvir wrote: > Dear all, > > > We have a structure of a rather tightly packed homotrimer protein in the ASU > with no apparent crystallographic or non-crystallographic rotational symmetry > between monomers. > Attempting to establish the biological assembly, we are very interested to > hear about additional similar cases you might know of. > > Thanks in advance, > Hay > > > --------------------------- > Hay Dvir Ph. D. > Head Technion Center for Structural Biology > Technion Haifa 3200003, Israel > Tel: +(972)-77-887-1901 > Fax: +(972)-77-887-1935 > E-mail hd...@technion.ac.il > Website http://tcsb.technion.ac.il >
