On Wednesday 05 May 2010 12:49:34 am Jon Wright wrote:
>
> I've been curious about this unit cell constant mis-matching for a
> while. If I understood well, Perutz tried to exploit the effect for
> phasing prior to heavy atom methods. As the unit cell changes, the
> diffraction peaks move, inte
Ian Tickle replied:
(freezing & soaking can easily induce > 1% and sometimes > 5% change),
is surely the reason that Fo-Fo maps never caught on!
I've been curious about this unit cell constant mis-matching for a
while. If I understood well, Perutz tried to exploit the effect
Ian's analysis is, as usual, much more sophisticated then my little
back-of-the-envelope calculation. I would like to make one philosophical
note: The non-isomorphism between the two crystals is not "noise" in the
Fo-Fo map, it is the whole point. Sometimes the non-isomorphism is
dominated by
Dale,
On Tue, May 4, 2010 at 12:19 AM, Dale Tronrud wrote:
> The greater the difference in cell constants the greater the "noise"
> in the map. I think the high resolution cutoff for the maps should
> be
>
> 2 A delta/(A+delta)
>
> where A is the cell edge with the largest change, and delta
I've struggled with getting CCP4 to calculate Fo-Fo maps, since I
usually use other software. The tricks are that the data sets have
to be scaled to each other in reciprocal space, and the maps calculated
with the same cell constants (which will be a lie for at least one of
them). The procedur
Hi Lucas,
phenix.fobs_minus_fobs_map
might work for you. Example:
phenix.fobs_minus_fobs_map f_obs_1_file=data1.mtz f_obs_2_file=data2.sca
f_obs_1_label=FOBS1 f_obs_2_label=FOBS2 model.pdb
where model.pdb is used as a source of phases for your map.
To be honest, I forgot how strictly I requ
Hi Everyone,
I've checked the previous posts about how to generate the difference
map from two crystals with different cell constants. I tried MAPMAN to
generate this map but I never got luck on this. It turned out to show
"Maps have different cell constants" every time. Does anyone know wh
