Just to clarify - I actually think the original assumption that Jacob posted is generally reasonable. But it needn't necessarily follow that the conformation we see in crystal structures is always representative of the solution state; given the extreme range of conditions in which crystals grow, I would be surprised if there weren't counter-examples. I'm not familiar enough with the literature on domain swapping (e.g. diptheria toxin) to know if any of those structures are crystal packing artifacts.
On Fri, Feb 10, 2012 at 1:04 PM, George <gkontopi...@vet.uth.gr> wrote: >>Packing billions of copies into a compact lattice > Not so compact there is 40-80% water >>freezing it to 100K > We have frozen many times protein solutions in liquid nitrogen and then thaw > and were working OK >> non-physiological amounts of salt and various organics > What is the amount of salt and osmotic pressure in the cell?? >>non-physiological pH too > What is the non-physiological pH too? I am sure that some enzymes they are > not working in pH 7. Also most of the proteins they have crystallized in pH > close to 7 so I would not say non-physiological. > > George > > PS There are lots of solution NMR structures as well supporting the > physiological crystal structures > > > -----Original Message----- > From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Nat > Echols > Sent: Friday, February 10, 2012 10:35 PM > To: CCP4BB@JISCMAIL.AC.UK > Subject: Re: [ccp4bb] Crystal Structures as Snapshots > > On Fri, Feb 10, 2012 at 12:29 PM, James Stroud <xtald...@gmail.com> wrote: >> How could they not be snapshots of conformations adopted in solution? > > Packing billions of copies of an irregularly-shaped protein into a > compact lattice and freezing it to 100K isn't necessarily > representative of "solution", especially when your solution contains > non-physiological amounts of salt and various organics (and possibly > non-physiological pH too). > > -Nat >
