Discussion Group

Discussion Group

Douglas Instruments and Jonathan Hadden started a discussion group in February 2005 for sharing general tips and techniques for protein crystallization, also as a forum for users of the Oryx and IMPAX robotic systems.

The group can be found at http://groups.google.com/group/oryx_group?hl=en

Experiment scripts for Oryx and Impax, crystal images etc. can be shared at the group web-site. The group is intended for non-commercial messages connected with protein crystallization only and it is coordinated by Jonathan Hadden at Leeds University.

The Douglas Instruments Discussion Group Archive (1999)

Douglas Instruments ran an informal discussion group 1999. The archive for this early discussion group can be found below.

Microbatch screening
VD equilibration with a single reservoir solution
Model proteins
Macroseeding, streak seeding, drop "feeding"

Microbatch screening
Douglas Instruments has found that microbatch is roughly as efficient at picking up new crystallization conditions in screening experiments as vapor diffusion, but it is much quicker, uses less protein and explores a different area of crystallization space. What are the experiences of other users of microbatch? Click here to reply

Response from Artem Evdokimov, Weizmann Institute, Israel

Response from Naomi Chayen, Imperial College, London

VD equilibration with a single reservoir solution
To save time and effort in both screening and optimization experiments using vapor diffusion, the same reservoir solution can be equilibrated against all droplets. Click here to reply

Response from Artem Evdokimov, Weizmann Institute, Israel

Model proteins
There is a need for a new model protein to replace lysozyme. Thaumatin and concanavalin A have been suggested, but there may be better alternatives. Click here to reply

Response from Artem Evdokimov, Weizmann Institute, Israel

Suggestions from Naomi Chayen, Imperial College, London: glucose isomerase, catalase

Detailed response from Marc Pusey, NASA at Huntsville AL

Response from the wilds of Cambridgeshire by Reuben Leberman

Macroseeding, streak seeding, drop "feeding"
Microbatch can easily be used for microseeding studies e.g. Korkhin and Evdokimov. Has anyone tried macroseeding, feeding (adding more protein and/or precipitant to a droplet containing crystals) or streak seeding with microbatch. Click here to reply

Response from Naomi Chayen, Imperial College, London

Microbatch optimization and data collection
When microbatch is used for optimization crystals are sometimes larger that with vapor diffusion, sometimes smaller, with the average being about the same. Click here to reply

Response from Naomi Chayen, Imperial College, London

To get the ball rolling, here are some more comments:

Crystals (especially needles and thin plates) can often be improved by using additives. We have suggested the automatic screening of additives using IMPAX or Oryx. Has anyone tried this? Click here to reply

Some scientists use IMPAX only for optimization. Another has used it almost continuously on a production-line basis since 1992 for screening, but never uses it for optimization. What are the pros and cons? Click here to reply

Douglas Instruments has software for rational experiment design, and has recently published a paper on this. Can good design allow one to find conditions more rapidly. Click here to reply

Microbatch is the most practical and economical method of crystallization for large-scale crystallization projects including structural genomics. Click here to reply

Patrick Shaw Stewart, April 1999