steps and problems for 3-D structure determination

Artem Evdokimov AEVDOKIMOZ at cinci.rr.com
Wed Sep 18 18:42:36 EST 2002


There is a number of books related to X-ray structure determination and NMR
structure determination. In order to fully grasp the issues your best bet
would be to take several courses - the material is extensive in both variety
of subjects and scopes of subjects.

In general, X-ray structure determination for macromolecules has two major
problems these days:

1) how to find conditions for diffraction-quality crystal growth
2) how to phase the data

Problem number 2 is well-studied and there are numerous methods to solve
it - while possibilities for improvement remain, they are constantly being
reviewed by a host of dedicated professionals.
Problem number 1 is VERY complex. Predicting of the 3D packing of an unknown
partially dynamic three-dimensional shape is, essentially, impossible.
Various empirical methods such as random and sparse-matrix semifactorial
screens, etc. give useful answers but not with 100% probability of success.
On top of this, not all proteins are initially purified in a form that is
crystallization-competent, so multiple cycles of protein engineering,
bio(physico)chemical characterization and purification are often necessary.

Hope this helps,

A.G.E.

"Marc Parisien" <parisien at iro.umontreal.ca> wrote in message
news:3D8798A5.310593D1 at iro.umontreal.ca...
> Hi All!
>
>     Where could I look for the steps involved in 3-D structure
> determination (either X-Ray or NMR), and also where in these steps are
> problems that could be resolved by computer and/or better algorithms. I
> would guess that the steps/problems are the same for either RNA or
> proteins?
>
>     thanks for your time,
>     Marc.
>





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