2 observations: 'collapsed' forms of calmodulin ligand also
exist that indicate the 'function' of wrapping
itself around a target.
Second, the real question is what the 'function' to be elucidated means - if
it involves a binding
site detail, resolution (i.e. coordinate precision) sure is 'biologically'
relevant.
In the case of Cam, a large domain movement as key part of the function
will be subject to all the well known crystal packing caveats and may
require
multiple structures etc.
I.e., to get the big picture, small detail is less relevant - as many
valuable low resolution structures (open-closed channels, etc) demonstrate.
BR
-----Original Message-----
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Jacob
Keller
Sent: Sunday, May 22, 2011 7:07 PM
To: [log in to unmask]
Subject: Re: [ccp4bb] Crystal structure and NMR structure
I think calmodulin is a classic example, in all its forms (I believe
that there are both NMR and crystal structures for all of these): +/-
calcium, +/- peptide. Especially the no-peptide +/- calcium forms
differ pretty substantially.
The calcium-bound no-peptide structures are particularly interesting,
as it seems that the NMR structure is much more plausible (take a look
if you don't believe me--the xtal structure has a really extended
alpha helix, which it seems to me would be bending all over the place
in solution). And yet, the crystal structure was solved at 1.0 Ang.
Now, assuming that the NMR structure is really a truer picture of the
structure in solution, this contradicts a premise which always seemed
reasonable to me, that as resolution increases, the model more
accurately represents the protein as found in solution. I guess the
bottom line is that resolution does not necessarily imply a better
picture of the molecule as it functions physiologically, but simply
means that the crystallography worked out better. Do others agree with
this, that resolution implies little about the physiological veracity
of the model?
Jacob
On Sat, May 21, 2011 at 4:03 AM, Chen Guttman <[log in to unmask]> wrote:
> Here you go:
> http://www.ncbi.nlm.nih.gov/pubmed/12015150
> Domain swapping of Cyanovirin.
> Chen
>
> ---
> Chen Guttman
> The Zarivach laboratory for Macromolecular Crystallography
> Building 39, Room 009B
> Ben-Gurion University of the Negev
> POBox 653
> Zip Code 84105
> Beer-Sheva
> Israel
> http://lifeserv.bgu.ac.il/wb/zarivach
> Tel. +972-8-6479519
> Fax. +972-8-6472970
>
>
> On Sat, May 21, 2011 at 08:34, Vandu Murugan <[log in to unmask]>
wrote:
>>
>> Dear all,
>> I would like to get some information on proteins where there is
>> conformation/structural change between the crystal structure and
solution
>> structure of the same protein. Do anybody came across such situations?
>> Thanks in advance..
>>
>> cheers,
>> Vandu
>
>
--
*******************************************
Jacob Pearson Keller
Northwestern University
Medical Scientist Training Program
cel: 773.608.9185
email: [log in to unmask]
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