Re: [ccp4bb] Why NCS doesn't help?

2009-07-08 Thread Eleanor Dodson

There are many reasons why this could have ocurred.
One is that your NCS operator is very close to being a crystallographic 
one.


But you need to give more details of the problem before I can comment 
sensibly

Eleanor

Sun Tang wrote:

Dear All,

In refining my structure (two molecules in au) that was solved with molecular 
replacement,  refinement starting with restrained lowered the R-free to about 
0.35 while with NCS increased the R-free to 0.55. Does it imply that two 
molecules are quite different or something wrong with the refinement?

Thank you very much for your suggestions?

Best wishes,

Sun Tang



  
  


Re: [ccp4bb] Why NCS doesn't help?

2009-07-08 Thread Sun Tang
Dear Eleanor,

Thank you very much for your reply. I think that the NCS operator is very close 
to the crystallographic two fold symmetry because when I searched for the 
solution with PHASER with one molecule as the model I could not find the 
solution so I have to use two molecules as the search model but I did 
not expect that will affect the NCS refinement. How to deal with this problem? 

Thank you very much for your great help! I also greatly appreciated all the 
replies to my question which help me clarify a lot.

Thank you All!

Best wishes,

Sun





From: Eleanor Dodson c...@ysbl.york.ac.uk
To: Sun Tang suntang2...@yahoo.com
Cc: CCP4BB@jiscmail.ac.uk
Sent: Wednesday, July 8, 2009 10:06:41 AM
Subject: Re: [ccp4bb] Why NCS doesn't help?

There are many reasons why this could have ocurred.
One is that your NCS operator is very close to being a crystallographic 
one.

But you need to give more details of the problem before I can comment 
sensibly
Eleanor

Sun Tang wrote:
 Dear All,

 In refining my structure (two molecules in au) that was solved with molecular 
 replacement,  refinement starting with restrained lowered the R-free to about 
 0.35 while with NCS increased the R-free to 0.55. Does it imply that two 
 molecules are quite different or something wrong with the refinement?

 Thank you very much for your suggestions?

 Best wishes,

 Sun Tang



      
  


  

[ccp4bb] Why NCS doesn't help?

2009-07-03 Thread Sun Tang
Dear All,

In refining my structure (two molecules in au) that was solved with molecular 
replacement,  refinement starting with restrained lowered the R-free to about 
0.35 while with NCS increased the R-free to 0.55. Does it imply that two 
molecules are quite different or something wrong with the refinement?

Thank you very much for your suggestions?

Best wishes,

Sun Tang