Re: [ccp4bb]: Thanks + short summary (crystallisation) from twinned to not twinned crystals

[Stefano Benini]

***  For details on how to be removed from this list visit the  ***
***          CCP4 home page http://www.ccp4.ac.uk         ***

Dear crystallisators,

first of all thanks to the people who replied and here it follows a 
summary:

1) try additives
2) DNA shuffling to introduce random mutations
3) agarose gel crystallisation
4) new construct ("having tried everything else for 3 years before...")
5) try to work on very small crystals and/or using a very small beam of 
a microfocus beamline at a synchrotron to isolate a single domain and 
get less twinning
6) destabilise the crystal to separate the two halves (when possible) as 
in http://www.sciencemag.org/cgi/data/311/5758/195/DC1/1
7) if the crystals are obtained with Mg exchange it to Mn
8) change in crystallisation pH
9) change in crystallisation temperature
10) suggestion (from a friend!!): " You can try switching proteins. 
Lysozyme usually does the trick."
11) co-crystallisation with partner proteins/domains or with ligands
12) another friend!!: "Hmmm. Who knows, eh?"
13) change crystallisation setup (e.g., from microbatch to hanging drops)
14) test crystals at room temperature as well: "(EBV protease) which 
became twins only upon freezing, at room temperature the crystals were 
untwinned (but resolution was much worse as well)"

I will add my suggestion as soon as I overcome my crystal twinning problem!!

thank you again
ciao
Stefano

**********************************
Stefano Benini Ph.D.
http://www.ysbl.york.ac.uk/~benini
York Structural Biology Laboratory
University of York
Heslington 
York YO10 5YW United Kingdom
Tel.:+44 1904 328276
Fax: +44 1904 328266
"verba volant scripta manent"
**********************************


Stefano Benini wrote:

***  For details on how to be removed from this list visit the  ***
***          CCP4 home page http://www.ccp4.ac.uk         ***



Dear crystallisators,

I would like to know what people usually tries (possibly succesfully!) 
to get not twinned crystals when a protein tends to crystallise as a 
perfect twin

I am trying/plannning to try: finding new conditions, additives, 
detergents, tag removed, new construct, etc.,

Thank you very much

Ciao
Stefano

**********************************
Stefano Benini Ph.D.
http://www.ysbl.york.ac.uk/~benini
York Structural Biology Laboratory
University of York
Heslington York YO10 5YW United Kingdom
Tel.:+44 1904 328276
Fax: +44 1904 328266
"verba volant scripta manent"
**********************************





--