Dear Rui,
Perhaps this is another
instance where the PX Scanner might prove
so helpful ? Maybe, amongst
your many crystals – all of which ‘look’
not too bad … there
are one or two which actually diffract much further
beyond the 2.9Ĺ which you
mentioned ? However, unfortunately, you’re
just not happening to choose
either of those for looping out.
The Oxford Diffraction PX
Scanner system can assess the diffraction
qualities of crystals in
situ - in the crystallisation plate.
So, directly, you would
discover if your crystals actually
diffract well... in their
mother liquor under ambient conditions
and before the addition of
any cryo-protect. Do you have a friend
or neighbour with a PX
Scanner ? If not, please feel most welcome
to contact Oxford
Diffraction: we would be pleased to assist if at
all possible.
Good Luck and Best Wishes,
Marcus Winter.
From:
CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of rui
Sent: 05 February 2010 14:48
To: [log in to unmask]
Subject: Re: [ccp4bb] how to
improve resolution
Hi, Thanks all for the
good suggestions, I just attached two images that show my crystals, maybe
you'll see new problems with the conditions. Thanks again.
On Fri, Feb 5, 2010 at 7:43 AM, Enrico Stura <[log in to unmask]> wrote:
On Fri, 05 Feb 2010
05:39:14 +0100, rui <[log in to unmask]>
wrote:
Hi, All,
We are trying to crystallize a protein and found some initial hit in the
following conditions,
pH 4.8, 0.2 M AS or some other salts ( NaCl,LiCl, MgCl2 ), 32% PEG4000 or
PEG3350 ). However the quality of the crystal is not so great,some of them
look like needle cluster(very long in length), some of them look like
multi-crystals or hollow inside.
Such growth problems are likely due to the quality of the protein
solution.
Changes in precipitant concentrations are likely to be ineffective. Try
ion exchange purification.