[phenixbb] RMS angles and comprehensive validation in phenix

Pavel Afonine pafonine at lbl.gov
Fri Sep 19 11:21:09 PDT 2014


Hi Ed,

yes, that's right. One is to detect severe outliers that may screw up 
the overall numbers. The other one is to compare these overall numbers 
with those derived from similar structures available in the data base.

Pavel

On 9/19/14 11:05 AM, Edward A. Berry wrote:
> Two different histograms involved here?
> For one structure, histogram of the deviations at all the different 
> bonds, angles
> For the entire PDB, histogram of rmsd of all the different structures
>
> On 09/19/2014 12:50 PM, Katherine Sippel wrote:
>> This is from Phenix's FAQ page...
>>
>> *"My resolution is X Angstroms; what should RMS(bonds) and 
>> RMS(angles) be?*
>>
>> This is somewhat controversial, but absolute upper limits for a 
>> well-refined protein structure at high resolution are typically 0.02 
>> for RMS(bonds) and 2.0 for RMS(angles); usually they will be 
>> significantly lower. As resolution decreases the acceptable deviation 
>> from geometry restraints also decreases, so at 3.5 Angstrom, more 
>> appropriate values would be 0.01 and 1.0."
>>
>> If the histogram shows that the RMS(angles) average higher than 2 
>> then I think that would be a result of poorly refined structures 
>> skewing the graph rather than a reflection of what the RMS should be.
>>
>>
>>
>> On Fri, Sep 19, 2014 at 1:57 AM, Pavel Afonine <pafonine at lbl.gov 
>> <mailto:pafonine at lbl.gov>> wrote:
>>
>>     Hi,
>>
>>     if you make sure these values are not caused by a handful of 
>> atoms that flew a distance apart for whatever reason then values like 
>> ok to me. This is why looking at a histogram of deviations (bond, 
>> angles etc) is way more useful than looking at just one number!
>>
>>     Pavel
>>
>>
>>     On 9/18/14 1:32 PM, C wrote:
>>>     Hi,
>>>
>>>     Refining using phenix I find the RMS angle drifting towards 
>>> 2.3-2.7 range when validating the resulting structure.
>>>
>>>     These are high resolution structures and I was wondering if 
>>> someone could comment on whether 2.3-2.7 values are worrisome?
>>>     Thank you
>>>
>>
>>
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>>
>>
>>
>> -- 
>> "Nil illegitimo carborundum"/- /Didactylos
>>
>>
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