Hi everyone, I am working with protein-ligand complex structure. For the head group in one of the ligands in the structure, two more positions in addition to the current position look possible according to the blue density in Coot. I am thinking of assigning multiple occupancies/positions to this head group. So, I am wondering what I should do to achieve this. Is the following strategy right? 1. Fit the head group to the density at three different positions separately in Coot and save them separately. 2. Find out the atoms that are different among the three ligand positions and combine the same atoms with different positions and change the occupancy of those atoms to something between 0 to 1. 3. Use Phenix. refine to refine. The occupancy refinement should be automatically on, right? Is this the best way to assign multiple occupancies/positions to the head group? Thank you so much! Also, anything to look after refinement which can tell me whether I am assigning the right multiple conformations to the ligand? Thank you so much! Best, Wei
Dear Wei, I would split the entire ligand in coot twice, not only the head. You can set the initial occupancy with coot, too. This has the advantage that the three conformation gain greater flexibility than what you might expect from the current density and, if the putatively non-disordered tail does not refine stably, you have a good indicator that you are overfitting and that e.g. your data are not strong enough for occupancy refinement. Best, Tim On 02/11/2014 05:35 AM, Wei Shi wrote:
Hi everyone, I am working with protein-ligand complex structure. For the head group in one of the ligands in the structure, two more positions in addition to the current position look possible according to the blue density in Coot. I am thinking of assigning multiple occupancies/positions to this head group. So, I am wondering what I should do to achieve this. Is the following strategy right? 1. Fit the head group to the density at three different positions separately in Coot and save them separately. 2. Find out the atoms that are different among the three ligand positions and combine the same atoms with different positions and change the occupancy of those atoms to something between 0 to 1. 3. Use Phenix. refine to refine. The occupancy refinement should be automatically on, right? Is this the best way to assign multiple occupancies/positions to the head group? Thank you so much! Also, anything to look after refinement which can tell me whether I am assigning the right multiple conformations to the ligand? Thank you so much!
Best, Wei
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Dear Tim,
Thank you so much for the suggestions. How can I split the entire ligand in
Coot? By adding "Ter" in the pdb text file? Thank you!
Best,
Wei
On Tue, Feb 11, 2014 at 3:55 AM, Tim Gruene
Dear Wei,
I would split the entire ligand in coot twice, not only the head. You can set the initial occupancy with coot, too. This has the advantage that the three conformation gain greater flexibility than what you might expect from the current density and, if the putatively non-disordered tail does not refine stably, you have a good indicator that you are overfitting and that e.g. your data are not strong enough for occupancy refinement.
Best, Tim
Hi everyone, I am working with protein-ligand complex structure. For the head group in one of the ligands in the structure, two more positions in addition to
On 02/11/2014 05:35 AM, Wei Shi wrote: the
current position look possible according to the blue density in Coot. I am thinking of assigning multiple occupancies/positions to this head group. So, I am wondering what I should do to achieve this. Is the following strategy right? 1. Fit the head group to the density at three different positions separately in Coot and save them separately. 2. Find out the atoms that are different among the three ligand positions and combine the same atoms with different positions and change the occupancy of those atoms to something between 0 to 1. 3. Use Phenix. refine to refine. The occupancy refinement should be automatically on, right? Is this the best way to assign multiple occupancies/positions to the head group? Thank you so much! Also, anything to look after refinement which can tell me whether I am assigning the right multiple conformations to the ligand? Thank you so much!
Best, Wei
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GPG Key ID = A46BEE1A
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Dear Wei, the refinement menu (Calculate -> Model/Fit/Refine...) contains "Add Alt Conf..." which, when applied to a ligand, splits the entire ligand into two (or three on the second go). You can modify occupancies and B-values with "Measures->Reside Info" Regards, Tim On 02/11/2014 02:00 PM, Wei Shi wrote:
Dear Tim, Thank you so much for the suggestions. How can I split the entire ligand in Coot? By adding "Ter" in the pdb text file? Thank you!
Best, Wei
On Tue, Feb 11, 2014 at 3:55 AM, Tim Gruene
wrote: Dear Wei,
I would split the entire ligand in coot twice, not only the head. You can set the initial occupancy with coot, too. This has the advantage that the three conformation gain greater flexibility than what you might expect from the current density and, if the putatively non-disordered tail does not refine stably, you have a good indicator that you are overfitting and that e.g. your data are not strong enough for occupancy refinement.
Best, Tim
Hi everyone, I am working with protein-ligand complex structure. For the head group in one of the ligands in the structure, two more positions in addition to
On 02/11/2014 05:35 AM, Wei Shi wrote: the
current position look possible according to the blue density in Coot. I am thinking of assigning multiple occupancies/positions to this head group. So, I am wondering what I should do to achieve this. Is the following strategy right? 1. Fit the head group to the density at three different positions separately in Coot and save them separately. 2. Find out the atoms that are different among the three ligand positions and combine the same atoms with different positions and change the occupancy of those atoms to something between 0 to 1. 3. Use Phenix. refine to refine. The occupancy refinement should be automatically on, right? Is this the best way to assign multiple occupancies/positions to the head group? Thank you so much! Also, anything to look after refinement which can tell me whether I am assigning the right multiple conformations to the ligand? Thank you so much!
Best, Wei
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-- Dr Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen
GPG Key ID = A46BEE1A
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Hi Wei, as long as your PDB file models altlocs like this: ATOM 5085 N AALA 270 19.772 -6.267 40.250 0.75 5.17 ATOM 5086 CA AALA 270 19.927 -5.299 41.342 0.75 5.15 ATOM 5087 CB AALA 270 20.132 -6.108 42.617 0.75 6.92 ATOM 5088 C AALA 270 21.058 -4.290 41.124 0.75 5.06 ATOM 5089 O AALA 270 20.831 -3.090 41.384 0.75 5.54 ATOM 5090 N BALA 270 19.733 -6.282 40.242 0.25 5.04 ATOM 5091 CA BALA 270 19.592 -5.512 41.492 0.25 5.03 ATOM 5092 CB BALA 270 19.702 -6.389 42.726 0.25 6.62 ATOM 5093 C BALA 270 20.673 -4.426 41.454 0.25 4.77 ATOM 5094 O BALA 270 20.381 -3.268 41.761 0.25 5.70 it's going to work in phenix.refine automatically. See more details here: http://phenix-online.org/documentation/refinement.htm#anch111 However placing a TER record between conformers ATOM 5085 N AALA 270 19.772 -6.267 40.250 0.75 5.17 ATOM 5086 CA AALA 270 19.927 -5.299 41.342 0.75 5.15 ATOM 5087 CB AALA 270 20.132 -6.108 42.617 0.75 6.92 ATOM 5088 C AALA 270 21.058 -4.290 41.124 0.75 5.06 ATOM 5089 O AALA 270 20.831 -3.090 41.384 0.75 5.54 TER ATOM 5090 N BALA 270 19.733 -6.282 40.242 0.25 5.04 ATOM 5091 CA BALA 270 19.592 -5.512 41.492 0.25 5.03 ATOM 5092 CB BALA 270 19.702 -6.389 42.726 0.25 6.62 ATOM 5093 C BALA 270 20.673 -4.426 41.454 0.25 4.77 ATOM 5094 O BALA 270 20.381 -3.268 41.761 0.25 5.70 will result in phenix.refine refining group occupancy of each conformer individually. Pavel
I am working with protein-ligand complex structure. For the head group in one of the ligands in the structure, two more positions in addition to the current position look possible according to the blue density in Coot. I am thinking of assigning multiple occupancies/positions to this head group. So, I am wondering what I should do to achieve this. Is the following strategy right? 1. Fit the head group to the density at three different positions separately in Coot and save them separately. 2. Find out the atoms that are different among the three ligand positions and combine the same atoms with different positions and change the occupancy of those atoms to something between 0 to 1. 3. Use Phenix. refine to refine. The occupancy refinement should be automatically on, right? Is this the best way to assign multiple occupancies/positions to the head group? Thank you so much! Also, anything to look after refinement which can tell me whether I am assigning the right multiple conformations to the ligand? Thank you so much!
Best, Wei
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participants (3)
-
Pavel Afonine
-
Tim Gruene
-
Wei Shi