I would agree with Mark. It would be also good to state that neither of us is cross-trained, but are one-trick dogs as far as NMR vs X-rays goes.
Still, I think that if you get any protein in good amounts, try to crystallize it (there are even good facilities for that these days, and funding to set up crystallization through Biostruct-X), and if that fails, consider NMR. Many good NMR labs try to crystallize their targets first - if it crystallizes its cheaper, easier and the structure is of higher resolution. Disclaimer: I am not saying NMR is useless - quite the contrary. But, I cant see why you would do an NMR structure of something that crystallizes in a straightforward cheap crystallization screen. I see why you might do NMR to answer many different questions. I will leave the membrane proteins question to experts - but these days we all see many membrane proteins coming from X-rays and as far as NMR goes you will be on the solid state regime and not solution as far as I understand: great promise, but again I suspect the impact to be different than 'structure solution'. A. On 9 Jun 2013, at 19:33, Mark van Raaij wrote: > Well, if you do NMR you avoid the possible bottlenecks of having to obtain > well-diffracting crystals, and having to phase the protein (i.e. obtain SeMet > protein crystals or suitable heavy atom derivatives; or a suitable MR model). > But instead, you'll need to prepare labelled protein (15N and/or 13C), which > is expensive and for which your protein needs to be able to be expressed in > minimal medium, and your protein will need to be very soluble, monodisperse > (in general monomeric) and stable in a minimal NMR-compatible buffer for data > collections lasting for hours. Assigning all the protons and calculating the > final structure can also be months of work, while a high-resolution crystal > structure can be finished in days, if the above-mentioned bottle-necks can be > overcome. > > > On 9 Jun 2013, at 17:36, Theresa Hsu wrote: > >> Dear all >> >> A question for the cross-trained members of this forum - for small sized >> proteins, is NMR better than crystallography in terms of data collection >> (having crystals in the first place) and data processing? How about membrane >> proteins? >> >> I would appreciate replies to the board, instead of off-board, to allow for >> a good discussion. >> >> Thank you. >> >> Theresa
