If you want to use se-Met, you might want to start by labeling only one protein at a time. For example, if you have A,B,C,D, grow crystals like this:
se-A, B, C, D A, se-B, C, D, etc. Then try combinations of 2, then 3, then if you haven't got the phases you need, try all 4. And remember, if 2 different combinations diffract and they are isomorphous, then you can try MIR too. Also, if your complex can stay intact on a gel shift, look at this paper: http://www.ncbi.nlm.nih.gov/pubmed/10903954 James On Jun 12, 2012, at 8:46 PM, LISA wrote: > Hi all, > > My work is to solve huge complex containing 4 different proteins and total > molecular weight is about 300 KD. I can purify the complex by co-expression > them in E.coli. This complex contains 8 protein A, 2 protein B and 1 protein > C and D. protein B and protein C have homology structures deposited in PDB > database. No homology structure available for protein A and D, which > contribute 60% of the whole molecular weight for the complex. > > Now I am trying to find a way to solve the phase of this complex. I am > thinking of use sad or mad with se-Met. There total 111 Met residues in > this complex. Is it possible to solve this complex by se-Met? Does someone > have experience to solve huge complex structure with se-met? It is also very > welcome for all the suggestion. Thank you. > > All the best, > > Lisa
