BIGGER is almost always BETTER if you spend the time to do your experiment
well, and in particular
freezing (flash-cooling) your crystal after an appropriate soak in a good
cryo-mixture that is respectful
of your crystal.
Thierry,
X-ray absorption, varies with the wavelength, and by going to shorter
wavelengths you can reduce
absorption. That will allow you some extra margin before you have a
crystal that is too big for
X-ray diffraction. At that point you can go to neutron diffraction and
position all your hydrogens
too!!
BIGGER is almost always BETTER!
AND
Jürgen,
I never said that you need to look ONLY at large crystals. I just said
that once you have extracted
as much information as possible from your small crystals, (if possible
consolidated
a structure at any resolution you can get), by improving your experimental
methodology, you should
aim towards BIGGER crystals, better Cryo-conditions and that WILL give you
higher resolution.
Refining a structure at 1.6-1.2A will be much easier than doing it at 3A
or lower. The time you spend
getting better crystals will save you a lot of time trying to get a decent
structure out of bad crystals.
BIGGER is almost always BETTER!
AND
Dirk Kostrewa,
Does stream-cooling beat liquid ethane as well or not?
Enrico.
On Tue, 07 Feb 2012 18:27:04 +0100, Fischmann, Thierry
<[email protected]> wrote:
-----Original Message-----
From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of
Enrico Stura
Sent: Tuesday, February 07, 2012 11:52 AM
To: [email protected]
Subject: Re: [ccp4bb] Freezing crystal
BIGGER is not always BETTER?
Theoretically it should be better because you have more scattering
matter.
Enrico: what you state above is only true if you ignore absorption of
the X-ray by the crystal.
Thierry
--
Enrico A. Stura D.Phil. (Oxon) , Tel: 33 (0)1 69 08 4302 Office
Room 19, Bat.152, Tel: 33 (0)1 69 08 9449 Lab
LTMB, SIMOPRO, IBiTec-S, CE Saclay, 91191 Gif-sur-Yvette, FRANCE
http://www-dsv.cea.fr/en/institutes/institute-of-biology-and-technology-saclay-ibitec-s/unites-de-recherche/department-of-molecular-engineering-of-proteins-simopro/molecular-toxinology-and-biotechnology-laboratory-ltmb/crystallogenesis-e.-stura
http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html
e-mail: [email protected] Fax: 33 (0)1 69 08 90 71
