Bret placed an Oryx1-6 robot in a Bactron X anaerobic chamber, and used mainly microbatch-under-oil crystallization to crystallize four proteins that are not stable in an environment with oxygen.  He found that microbatch avoided the need for frequent degassing of solutions which reduced the work-load enormously.  The oil also provided extra protection from oxidation.

One of the proteins crystallized is rubrerythrin from the hyperthermophilic archaeon, Pyrococcus furiosus.  The native protein contains iron, but is unstable in oxygen.  A previously-reported structure was determined in the presence of oxygen, but the iron had been replaced by zinc.  Using the anaerobic system, Bret has now obtained the native form containing iron.

Ammonium sulfate was the most popular precipitant with 900 entries, followed by PEG 4K (710 entries) and PEG 8K (488 entries).  However, if you combine the medium and high molecular-weight PEGs (1968 entries) they easily outnumber ammonium sulfate.

The table also gives the average concentrations used.
 

The results for Oryx were comparable with the four other nano-dispensing robots tested (and in some cases significantly better). 

For example, 100 nl volumes of 6 different concentrations each of PEG 10K, PEG 3K, isopropanol and MPD were dispensed. Excluding concentrations above 45% (where some material was carried on the outside of the tip) an average of 93 nl was dispensed with a CV of 14.8%.

For the 'sticky' protein with glycerol and detergent, Oryx's CV was 13% for 20 nl drops - although such small volumes are not normally recommended!
 

Douglas Instruments is very happy to announce the winner of the first round of its competition for the best use of its Vapor Batch and Crystal Clear crystallization plates.

The prize was won by the only entrant, Dr. Lesley Haire, from the National Institute of Medical Research, London, UK.

Lesley showed that the Vapor Batch plates are ideal for growing and harvesting crystals that require volatile organic materials such as isopropanol.  Crystals of a hexameric form of the NTD of the capsid protein of N-MLV were grown by dispensing protein and PEG into wells on the Vapor Batch plate.  The drops were covered with "Al's Oils" (a 50:50 mixture of silicone and paraffin oils).  Isopropanol solution was placed in the trough around the outside of the plate, so that the isopropanol could diffuse through the oil into the drops.  This approach allowed crystals to be harvested without damage.

Douglas Instruments and Jonathan Hadden have started a discussion group for sharing general tips and techniques for protein crystallization, and also as a forum for users of the Oryx and IMPAX robotic systems.  The group can be found at http://clubs.wanadoo.co.uk/groups/oryx-impax  Experiment scripts for Oryx and Impax, crystallization 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.

Douglas Instruments has introduced new scripts for Oryx which allow it to dispense sitting drop experiments down to 100 nl + 100 nl.  Much greater accuracy and more reliable dispensing is achieved by lifting up the tip a few tenths of a mm while simultaneously dispensing protein and screening solution.  (Oryx only dispenses the drops - it is not recommended for filling the reservoirs of vapor diffusion experiments.)  
 
 Existing users of Oryx should contact Douglas Instruments to obtain software that includes these scripts.

Douglas Instruments has released a version of XStep, its optimization software, which can export experimental data in XML format.  For a sample file, please click here.
 
Xstep gives a simple-to-use spreadsheet environment where values can be interpolated between wells in opposite corners of a plate.  It also generates experiments with multivariate designs such as Box-Behnken and Central Composite.   
 
XML is a standard that can be read by most databases, spreadsheets etc.  It represents data using a hierarchical structure - this makes it easy for the importer to reorganize the data and to ignore branches that contain data that is not of interest.