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

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From: Daniele de Sanctis de {- dot -} sanctisd {- at -} GMAIL {- dot -} COM
Date: 2008-05-15

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Subject: Re: poll: cutoff for "high resolution"
From: William Scott wgscott {- at -} CHEMISTRY {- dot -} UCSC {- dot -} EDU
Date: 2008-05-15

Subject: Re: poll: cutoff for "high resolution"
From: Ed Pozharski epozh001 {- at -} UMARYLAND {- dot -} EDU
Date: 2008-05-15

I don't think that individual atoms can be RESOLVED at 2A resolution.
Even if we forget that hydrogen is also an atom, it is still true that
peaks in electron density corresponding to, say, covalently bonded atoms
are not separated. If atomic positions at 2A would be over-determined,
we won't need geometry restraints. Atomic resolution begins somewhere
around 1.2A (not surprisingly since this is about the length of covalent
bond). I think there is some confusion regarding the term "atomic
resolution" because at some point in the past it signified the ability
to refine atomic positions (vs just threading CA backbone through tubes
of density). But then I am not old enough to pretend to be an expert on
this.

Cheers,

Ed.

On Thu, 2008-05-15 at 12:11 -0400, 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,
>
--
Edwin Pozharski, PhD, Assistant Professor
University of Maryland, Baltimore
----------------------------------------------
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Then knowledge and wisdom are born along with hypocrisy.
When harmonious relationships dissolve then respect and devotion arise;
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CCP4bb <-- 2008 <-- May 2008 <-- 15 May 2008

Previous message:
Subject: COURSE ANNOUNCEMENT - BIOCRYS 2008
From: Daniele de Sanctis de {- dot -} sanctisd {- at -} GMAIL {- dot -} COM
Date: 2008-05-15

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Subject: Re: poll: cutoff for "high resolution"
From: William Scott wgscott {- at -} CHEMISTRY {- dot -} UCSC {- dot -} EDU
Date: 2008-05-15