----- Original Message -----
From: "Jenny Martin" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, August 23, 2007 5:46 PM
Subject: Re: [ccp4bb] The importance of USING our validation tools
My question is, how could crystals with 80% or more solvent diffract so
well? The best of the three is 1.9A resolution with I/sigI 48 (top shell
2.5). My experience is that such crystals diffract very weakly.
You must be thinking about Mark van Raaij's T4 short tail fibre structures.
Yes, the disorder in those crystals is extreme. There are ~100-150 A thick
disordered layers between the ~200 A thick layers of ordered structure. The
diffraction pattern does not show any anomalies (as far as I can remember
from 6 years ago). The spots are round, there are virtually no spots not
covered by predictions, and the crystals diffract to 1.5A resolution. The
disordered layers are perpendicular to the threefold axis of the crystal.
The molecule is a trimer and sits on the threefold axis. It appears that the
ordered layers somehow know how to position themselves across the disordered
layers. I agree here with Michael Rossmann that in these crystals the
ordered layers are held together by faith.
Mark integrated the dataset in lower space groups, but the disordered stuff
was not visible anyway. He will probably add more to the discussion.
Petr
Any thoughts?
Cheers,
Jenny
