The Diffuse Scatter challenge

The challenge:

I dare anyone to figure out what the protein motion is that is causing the diffuse scatter in this data set: img files

You will never find a more straightforward diffuse-scatter problem. This is lysozyme. And the data are simulated from a single, simple motion. All of the diffuse scatter comes from this motion. There are no contributions from the lattice, no "centrosymmetric term" from the B factors, no correlations between unit cells, or even correlations between asymmetric units. Each lysozyme molecule is moving independently of all the others. There are also no overloads, no read-out noise, pixel blooming or other detector artefacts. Not exactly "realistic", but simple. Simple as it can possibly be. If anyone figures it out, then I can make start making this more realistic.

Note, the Bragg peaks in these data are not just ornamental. They correspond to the avearge electron density, and you should be able to process these images with XDS, mosflm, denzo or whatever data processing program is your favorite. The diffuse scatter has the same orientation matrix as the Bragg data.

Why?

Lots of people have diffuse scatter, and we know it comes from correlated motions in the crystal. Simulating the diffuse scatter from a given motion is straightforward (as I have done here), but what about the other way around? Short of actually cheating (see below), can you figure this out?

Where did these data come from?

They are from simulated diffraction patterns of the classic tetragonal crystal form of gallus gallus egg lysozyme.

What constitutes "cheating"?

For the results of this challenge to be useful to practicing crystallographers (both those of us who use software and those who develop it) your "solution" to this problem must be a plausible "before you knew the right answer" scenario. The "right answer" is located here: (30 pdb files). simply computing the diffuse scatter from these is definitely cheating.

Anything else, at this point, I'd say is great!.

So, is there anyone out there who can derive dynamics from diffuse scatter? Anyone?

If you think you have found a way to solve this without "cheating" in any way, let me know! I will re-name the challenge after you.

James Holton <JMHolton@lbl.gov>