On Thu, 2012-12-13 at 17:50 +0000, Theresa Hsu wrote:
> Being a beginner crystallographer, may I ask a basic question? On how
> many occasions does it make a *biological* difference between having a
> structure at 1.42 and 1.6 A?
And your definition of "biological difference" is exactly what? Every
field of experimental science strives to obtain results of best possible
quality, why should macromolecular crystallography be different? Would
you be satisfied with a report that "binding assays show presence of
binding which perhaps is in submicromolar range but we don't care to
determine actual binding constants"?
You should also realize that while ccp4bb has evolved over years into a
forum covering topics well beyond computational aspects of
macromolecular crystallography, at its core it still is made of
individuals who value method development. As Black Queen told Alice -
it takes all the running you can do to keep in the same place.
> I think this question also extends to adding in water molecules just
> to make statistics look good.
I never understood this attitude. Compared to O/CNS combination on SGIs
(which are all excellent products) refining a model using COOT/REFMAC on
a modern Core i7 machine is a cakewalk. Let's see - one spends from
several months to a year or two going from gene to diffraction data, and
spending a week carefully rebuilding in order to obtain the best most
complete model possible is undue burden? I am not a perfectionist by
any measure, but deliberately not placing water molecules that you can
place because it "does not make biological difference" can hardly be
justified.
Cheers,
Ed.
>
--
Oh, suddenly throwing a giraffe into a volcano to make water is crazy?
Julian, King of Lemurs
