Re: [ccp4bb] poll: cutoff for "high resolution"

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CCP4bb <-- 2008 <-- May 2008 <-- 15 May 2008

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Subject: Re: poll: cutoff for "high resolution"
From: "Bryan W {- dot -} Lepore" Bryan {- dot -} Lepore {- at -} UMASSMED {- dot -} EDU
Date: 2008-05-15

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Subject: Re: poll: cutoff for "high resolution"
From: Bernhard Rupp bernhardrupp {- at -} SBCGLOBAL {- dot -} NET
Date: 2008-05-15

Subject: Re: poll: cutoff for "high resolution"
From: Sue Roberts suer {- at -} EMAIL {- dot -} ARIZONA {- dot -} EDU
Date: 2008-05-15

I don't think the term "high resolution" has any real definition or
meaning anymore. If you're proud of the resolution, put the number in
the title of the paper and let the reader decide. At one time 2 A was
high resolution, but I wouldn't consider that high resolution today
for a plain vanilla protein structure.

The optical resolution is ~ 0.7 x the spacing at which the diffraction
is cut off as a best possible case - SFCHECK gives an estimate of the
optical resolution. Since hydrogen atoms are not really visible, even
at very high resolution, I'd call atomic resolution that resolution
at which atoms in C=O bonds are resolved or ~ 1.2 A.

I used to think using atomic resolution as a descriptor was safe (I
think the shelx and acorn documentation uses 1.2 A in this definition)
until I attended a seminar entitled
"Atomic resolution structure of (some membrane protein - I don't
remember which one) and found it to be a solid state NMR study where
they could figure out
the direction in which a helix was running (and could therefore build
a helix.)

Sue

On May 15, 2008, at 9:11 AM, proclus@GNU-DARWIN.ORG wrote:

> On 14 May, Mark Del Campo wrote:
>> At what refinement resolution or resolution ranges would you call a
>> structure "high resolution" vs.
>> "low resolution"? I realize that this may boil down to semantics
>> (e.g. some may classify structures as
>> "medium resolution"), but I wanted to get an opinion from the pros.
>
> A sensible definition of high resolution would be that resolution at
> which the structure is computationally over-determined, which is about
> 2 angstroms or better for a complete data set. This would also be a
> sensible definition for what is called atomic resolution, because the
> atoms are resolved as spheres or better, so that the position is
> over-determined.
>
> Regards,
>
> --
> Michael L. Love Ph.D
> Department of Biophysics and Biophysical Chemistry
> School of Medicine
> Johns Hopkins University
> 725 N. Wolfe Street
> Room 608B WBSB
> Baltimore MD 21205-2185
>
> Interoffice Mail: 608B WBSB, SoM
>
> office: 410-614-2267
> lab: 410-614-3179
> fax: 410-502-6910
> cell: 443-824-3451
> http://www.gnu-darwin.org/
>
> Visit proclus realm! http://proclus.tripod.com/
> -----BEGIN GEEK CODE BLOCK-----
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Dr. Sue A. Roberts
Biochemistry & Biophysics
University of Arizona
520 621 8171
suer@email.arizona.edu

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CCP4bb <-- 2008 <-- May 2008 <-- 15 May 2008

Previous message:
Subject: Re: poll: cutoff for "high resolution"
From: "Bryan W {- dot -} Lepore" Bryan {- dot -} Lepore {- at -} UMASSMED {- dot -} EDU
Date: 2008-05-15

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Subject: Re: poll: cutoff for "high resolution"
From: Bernhard Rupp bernhardrupp {- at -} SBCGLOBAL {- dot -} NET
Date: 2008-05-15