Does 
    unset normalize_ccp4_maps
in pymol (http://www.pymolwiki.org/index.php/Normalize_ccp4_maps)
overcome your problem?

On Wed, Jul 21, 2010 at 11:01:20AM -0400, Andy Torelli wrote:
>       I just realized it's the "mapmask" program.  Documentation at:  
> www.ccp4.ac.uk/dist/html/mapmask.html
>
>       The SCALE [SIGMA [c1 [c2]]] seems to be promising.  I'll give that a 
> try.
>
> Thanks,
> -Andy
>
> On 7/21/2010 10:34 AM, Andy Torelli wrote:
>> Kevin,
>>
>>      Thank you for the reply.  Your suggestion works well.
>>
>>      As a follow-up question, I noticed that extending the map has changed
>> the sigma level that must be chosen in PyMOL in order to match the view
>> in COOT.  Is this because the sigma level is defined based on the
>> distribution of electron density and by changing the extent of the map I
>> have changed the distribution of electron density peaks?
>>
>>      If so, I'd like to normalize the new map to the original map in order
>> to get the sigma contouring to match.  I expect the program
>> documentation may help with this.  Do you know which program is used for
>> the "Extend a map/mask file" function you mentioned?
>>
>> Thank you very much for your time,
>> -Andy
>>
>> On 7/21/2010 10:02 AM, Kevin Cowtan wrote:
>>> The ccp4 program mapmask does what you want. From ccp4i, select:
>>> Map and Mask Utilities/Edit-Rotate Map&   Mask/Extend a map-mask file
>>>
>>> Andy Torelli wrote:
>>>> Hi everyone,
>>>>
>>>>       I produced an NCS-averaged map in COOT that I would like to output
>>>> and load into PyMOL to make a figure.  The map loads successfully into
>>>> PyMOL, but of course the density only covers a portion of my molecule
>>>> that is fully covered when viewed in COOT.  I know/believe this is
>>>> because COOT generates maps with electron density that is only defined
>>>> explicitly for certain regions of the unit cell and dynamically displays
>>>> electron density (based on symmetry) for the regions that are not defined.
>>>>
>>>>       I e-mailed the PyMOLbb regarding this issue some time ago and
>>>> learned that symmetry-expansion was in the works, but it doesn't seem to
>>>> be working in version 1.2r3pre.  I was wondering if there is any way to
>>>> tell COOT to output a map with electron density values explicitly
>>>> defined for a given region (e.g. a protein chain, defined region of
>>>> space or a ligand/ion).
>>>>
>>>> Things I've tried:
>>>>    - making a mask (Extensions->Maps->Mask Map by Atom Selection) and
>>>> loading that map into PyMOL based on a previous post suggestion, but the
>>>> (lack of) coverage was the same.
>>>>    - loading the map into MAPMAN and converting to a different file
>>>> format.  The map was too big to be loaded and I'm not sure if I can
>>>> re-define the area for which electron density will be defined.
>>>>
>>>> Thanks for your help and suggestions,
>>>> -Andy Torelli
>>>
>>>
>>

-- 
--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen

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