[Chimera-users] disulfide bonds ?

Marek Maly marek.maly at ujep.cz
Tue Jul 15 14:41:57 PDT 2014


OK, thanks again,

    Best wishes,

     Marek

Dne Tue, 15 Jul 2014 23:38:10 +0200 Eric Pettersen <pett at cgl.ucsf.edu>  
napsal/-a:

> Thanks for the input files.  I'm happy to report the problem is indeed  
> fixed.
>
> --Eric
>
> On Jul 15, 2014, at 1:57 PM, "Marek Maly" <marek.maly at ujep.cz> wrote:
>
>> Hi Eric,
>> thanks for your decisions.
>>
>> Sorry that I forget to send my files for testing.
>> I was fully satisfied just with the complete explanation of
>> this Chimera strange behavior :))
>>
>> I will send you my input files off-line.
>>
>>  Best wishes,
>>
>>      Marek
>>
>>
>>
>>
>> Dne Tue, 15 Jul 2014 20:42:39 +0200 Eric Pettersen <pett at cgl.ucsf.edu>  
>> napsal/-a:
>>
>>> Hi Marek,
>>> 	I'm glad my suggestion worked.  I agree with you assessment, which is  
>>> why I was hoping you could provide data files for testing.   
>>> Nonetheless, I have gone ahead and made changes such that for formats  
>>> where explicit topology files are provided, such as Amber, Chimera  
>>> "trusts" the connectivity and does not change excessively long bonds  
>>> into pseudobonds.  Those changes will be in tonight's daily build and  
>>> I'm hoping you can test them and let me know if they work.  Look for  
>>> daily builds dated July 15th or later.
>>>
>>> --Eric
>>>
>>> On Jul 15, 2014, at 4:08 AM, "Marek Maly" <marek.maly at ujep.cz> wrote:
>>>
>>>> Hi Eric,
>>>> thank you for the prompt and useful answer.
>>>>
>>>> The approach you suggested works !
>>>>
>>>> But I already identified the source of the problem.
>>>>
>>>> In my Amber MD trajectory, there was also the first(starting)
>>>> configuration of my protein (that from the *.inpcrd file).
>>>>
>>>> This starting configuration was not so precise as was obtained
>>>> by the electron microscopy (not by X-ray or NMR technique).
>>>>
>>>> From this reason distances of some of the sulfur atoms which should  
>>>> be connected
>>>> by disulfide bond was not reasonable in this starting configuration  
>>>> but higher like 3 A or 6 A.
>>>>
>>>> So in spite the fact that in the Amber topology (*.prmtop) file were
>>>> clearly written all the disulfide bonds, Chimera evidently ignored
>>>> those bonds in sulfur atom pairs where the distance was not in the
>>>> reasonable range (close to 2A). Instead perhaps Chimera considered,  
>>>> that there
>>>> are some missing parts or so and used "dashed line" instead "stick".
>>>> So this was the first Chimera "mistake" which should not happen if  
>>>> she just simply
>>>> accepted the full topology information from the "*.prmtop" file.
>>>>
>>>> Another problem was that even if in all consequent frames of the  
>>>> trajectory
>>>> all the relevant sulfur atoms were in the reasonable distance (2-2.1  
>>>> A - due to the fact
>>>> that during the Amber simulation they were bonded), Chimera doesn't  
>>>> care about because
>>>> she evaluate the overall structure just using the first frame of the  
>>>> trajectory.
>>>>
>>>> I would suggest here, that Chimera should not take her own decisions  
>>>> in such cases when
>>>> molecular topology is fully defined in input files (e.g. Amber  
>>>> *.prmtop, mol2 etc.).
>>>>
>>>> Especially in case of the Amber *.prmtop file it is clear that  
>>>> structure should be OK,
>>>> (e.g. without the missing parts) because otherwise this topology file  
>>>> would never be created.
>>>>
>>>> If Chimera find something strange in the structure (even if this  
>>>> structure was fully
>>>> determined in the input file/s), she can always write the proper  
>>>> warnings, and that
>>>> should be enough in such specific cases, I think.
>>>>
>>>> Best wishes,
>>>>
>>>>     Marek
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Dne Mon, 14 Jul 2014 19:33:51 +0200 Eric Pettersen  
>>>> <pett at cgl.ucsf.edu> napsal/-a:
>>>>
>>>>> On Jul 14, 2014, at 8:57 AM, "Marek Maly" <marek.maly at ujep.cz> wrote:
>>>>>
>>>>>> Hellow,
>>>>>>
>>>>>> I just visualized my Amber MD trajectory with protein containing
>>>>>> several disulfide bonds. These bonds as well as all the other bonds  
>>>>>> are
>>>>>> written in the given Amber topology (*.prmtop) file, which is read  
>>>>>> in
>>>>>> by Chimera. Moreover the distance of sulfur atoms connected by  
>>>>>> disulfide bond
>>>>>> is in all cases quite reasonable ( 2-2.1 A). In spite these facts  
>>>>>> Chimera
>>>>>> draws some of those bonds in "stick" and some of them in "dashed  
>>>>>> line" style,
>>>>>> even if one sets globally "stick" or "ball & stick" representation.
>>>>>> Please see the attached illustrations.
>>>>>>
>>>>>> Why Chimera is doing such unwanted differences in graphical  
>>>>>> representations here ?
>>>>>>
>>>>>> It is possible, to force Chimera to draw all of those bonds  
>>>>>> unanimously in "stick"
>>>>>> representation ?
>>>>>
>>>>> Hi Marek,
>>>>> 	My best guess is that Chimera is mistakenly converting some of the  
>>>>> the disulphide bonds into "missing structure" pseudobonds, which are  
>>>>> supposed to be used to represent parts of a chain that missing  
>>>>> because is couldn't be located in the experimental data -- which  
>>>>> obviously is not the case here!  The workaround to make those  
>>>>> pseudobonds be depicted as stick is to open the Pseudobond Panel (in  
>>>>> Tools/General Controls) and the double click on the "missing  
>>>>> structure" group to bring up its attribute inspector.  In that  
>>>>> inspector, click the check box next to "Component Pseudobond  
>>>>> Attributes" to reveal those options and then change "bond style"  
>>>>> from wire to stick.  There is an equivalent command:  "setattr pb  
>>>>> drawMode 1".
>>>>> 	Obviously the better solution is to have Chimera not make this  
>>>>> mistake in the first place.  As far as I know it shouldn't be  
>>>>> already.  So, I would need your prmtop file and at least a subset of  
>>>>> your coordinate file in order to investigate.  Also, what version of  
>>>>> Chimera are you using?
>>>>>
>>>>> --Eric
>>>>>
>>>>>                       Eric Pettersen
>>>>>                       UCSF Computer Graphics Lab
>>>>>                       http://www.cgl.ucsf.edu
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> __________ Informace od ESET NOD32 Antivirus, verze databaze 10094  
>>>>> (20140714) __________
>>>>>
>>>>> Tuto zpravu proveril ESET NOD32 Antivirus.
>>>>>
>>>>> http://www.eset.cz
>>>>>
>>>>
>>>>
>>>> --
>>>> Tato zpráva byla vytvořena převratným poštovním klientem Opery:  
>>>> http://www.opera.com/mail/
>>>
>>>
>>> __________ Informace od ESET NOD32 Antivirus, verze databaze 10101  
>>> (20140715) __________
>>>
>>> Tuto zpravu proveril ESET NOD32 Antivirus.
>>>
>>> http://www.eset.cz
>>>
>>>
>>>
>>
>>
>> --
>> Tato zpráva byla vytvořena převratným poštovním klientem Opery:  
>> http://www.opera.com/mail/
>
>
> __________ Informace od ESET NOD32 Antivirus, verze databaze 10101  
> (20140715) __________
>
> Tuto zpravu proveril ESET NOD32 Antivirus.
>
> http://www.eset.cz
>
>
>


-- 
Tato zpráva byla vytvořena převratným poštovním klientem Opery:  
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