[ccp4bb] how to improve resolution

- Protein crystallography

Main steps:

- Protein purification
- Crystallisation

Special:

- Programs for crystallography
- X-ray detectors

Basic tutorials:

   - Chemistry
   - Protein
   - Peptide
   - Amino Acids

Xtal community:

- CCP4BB

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: how to improve resolution
From: rui ruisher {- at -} GMAIL {- dot -} COM
Date: 2010-02-05

Next message:
Subject: Re: ccp4-6.1.3 phaser sigmaa weighted maps problem
From: hari jayaram harijay {- at -} GMAIL {- dot -} COM
Date: 2010-02-05

Subject: how to improve resolution
From: Marcus Winter Marcus {- dot -} Winter {- at -} OXFORD-DIFFRACTION {- dot -} COM
Date: 2010-02-05

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 2.9Å 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.

www.oxford-diffraction.com

________________________________

From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of rui
Sent: 05 February 2010 14:48
To: CCP4BB@JISCMAIL.AC.UK
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 wrote:

On Fri, 05 Feb 2010 05:39:14 +0100, rui 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.

We tried to optimize the pH and PEG and
tested one that diffracts at 2.9A. For the next, how to improve
resolution?Any suggestions? Even mutate the protein to get a high resolution
is ok, generally what kind of mutation would make proteins crystallize
better? Thanks.

It is not mutations that will improve diffraction, it is small changes
in crystal contacts.
The Discussion section from:
http://pubs.acs.org/cgi-bin/article.cgi/cgdefu/2007/7/i11/html/cg700698d.html

may help.

Enrico

--
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, CEA Saclay, 91191 Gif-sur-Yvette
Cedex FRANCE http://www-dsv.cea.fr/en/ibitecs/82
http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html
e-mail: estura@cea.fr Fax: 33 (0)1 69 08 90 71

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: how to improve resolution
From: rui ruisher {- at -} GMAIL {- dot -} COM
Date: 2010-02-05

Next message:
Subject: Re: ccp4-6.1.3 phaser sigmaa weighted maps problem
From: hari jayaram harijay {- at -} GMAIL {- dot -} COM
Date: 2010-02-05