Robotic crystallisation refinement

If you already have some idea about how your protein crystallises, (by screening at the C3 for example), you may wish to refine those crystallisation conditions in order to produce crystals which are suitable for further studies. This is also known as optimisation. At Bio21 C3 we offer optimisation services where we set up your sample in the optimisation plates that you request

At the CSIRO node of the Bio21 C3 we offer a number of crystallisation optimisation techniques which have been adapted to work in our standard 96 well SD-2 sitting drop trays.

We need between 20-40µl of protein solution to set up an optimisation plate, depending on the droplet size and the type of experiment. Click here to find a more complete description of how much protein solution we need from you.

Fine Screening

We can design and dispense a custom screen which focuses in on a small set of chemicals.  These can be either grid screens or more random combinations of chemicals.  You can use the viewing software CTweb can be used to create both random and grid type optimisation screens from one or many initial hits, or you can work with the staff at C3 (c3@csiro.au) to create your optimisation screens

Additive Screening

An initial crystallisation condition is explored by doping that condition with a number of disparate chemicals, and using these in a crystallisation experiment.  We use a number of different additive screens, including the Additive Screen 96, Silver Bullet screen and Detergent Screen HT from Hampton Research, as well as The OptiSalt Suite from Qiagen. 
*Note that detergent additive screens require the use of the Mosquito robot, and incur a plate surcharge.

Microseeding

If you have crystals, but have problems reproducing them, or you would like to explore crystallisation screening using seeding, then we can use CSIRO’s Mosquito robot in combination with the Bio21 Phoenix robot to set up microseeding experiments. These experiments incur the Mosquito plate surcharge

Kinetic variations

One way to improve crystal quality is to modulate the rate at which crystals grow.  We can do this by altering the size of the crystallisation droplet, from 200 nl total initial drop volume to 1 ml total initial drop volume.  We can also alter the ratio of the droplet components, bearing in mind that the smallest individual volume that we can dispense is 100 nl.  We can also set up droplets against gradients of reservoirs

Click here to access a paper which describes all of these techniques in more detail.