Hi, Did you check for the 2N,2O coordination. Does your protein has copper ion as cofactor, whats the pH of the buffer. And if pH below 6 we can partially eliminate the speculation of copper ion.
S.Jayashankar Research Student Institute for Biophysical Chemistry Hannover Medical School Germany. On Tue, Jul 7, 2009 at 10:13 PM, Van Den Berg, Bert < [email protected]> wrote: > Dear all, > > > I have attached a jpeg of some (2fo-fc) density in the active site of a > protein I'm refining (1.9 A data, Rfree 24%, still need to pick waters > etc; oxygen atom placed in the approximate center for reference). It > looks like there are 3 non-hydrogen atoms sandwiched between an Asp, His > and Arg. The molecule seems hydrogen bonded to all these three residues. > Has anybody any idea what this can be? In a map of another crystal of > the same crystal form at lower res (2.3 A), there is a clear, single > water molecule between the Asp and His. Are they waters at partial > occupancies (there is not enough room for 3 separate waters)? The only > other thing I can come up with is formate, but that wasn't used in the > crystallization. > > Any hints appreciated! > > Thanks, Bert > > > Bert van den Berg > UMass Medical School > Worcester, MA 01605 > > >
