One major factor that increases the difficulty of finding a satisfactory
MR solution (assuming a good search model) is the number of molecules
that need to be placed in the ASU. Most programs can typically easily
and quickly find a solution for one molecule per ASU. Placing three
molecules per ASU can be trying. We've found that either Phaser or EPMR
(now Open-EPMR) is able to crack many of the most difficult problems.
Both of the programs have the advantage of being very fast and require
little fiddling and manual intervention.
Cheers,
___________________________________________
Roger S. Rowlett
Professor
Department of Chemistry
Colgate University
13 Oak Drive
Hamilton, NY 13346
tel: (315)-228-7245
ofc: (315)-228-7395
fax: (315)-228-7935
email: [EMAIL PROTECTED]
-----Original Message-----
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On
Behalf Of Jay Thompson
Sent: Saturday, May 12, 2007 6:52 PM
To: [email protected]
Subject: [ccp4bb] Mol Rep in high symmetry spacegroups
Hi All,
I have a question- kinda general though. I've always heard of
stories from people that molecular replacement is often difficult in
high symmetry space groups, like R32, cubic, etc... I'm not quite sure
I understand why that is the case? Is the molecular replacement
difficult because in high symmetry space groups you have so many
molecules in the unit cell and therefore the patterson vectors becomes
more complicated and therefore more difficult to find a match during
cross rotation/translation? If this is the case, I'm wondering if this
is still a problem with today's computers and software? Do people have
a favorite molecular replacement program they like to use specifically
in high symmetry space groups? or are there programs that don't handle
high symmetry space groups very well? Do people have a preference
between Amore, Phaser, MolRep, epmr, and CNS? Any anecdotes would be
appreciated. Thanks in advance!
Jay
