How do I crystallise my protein: What screens do I use?

There are many different crystallisation screens from both commercial and academic sources that are suitable for protein crystallisation. Whilst it may be tempting to try large numbers of screens, this can be difficult to keep track of and systematically work through the results. In addition, many commercial screens from different companies are essentially duplicates so you may be wasting effort and precious protein samples. An addition burden is that these experiments can be time consuming and costly and thus we now approach the crystallisation of new candidate proteins via the following route. Our crystallisation robots and imaging systems will make setting up these experiments quick and easy and hopefully much more systematic.

For most soluble proteins, take the following path below to obtaining initial hits. For membrane proteins and protein complexes we have alternative screens. The strategy outlined below is denoted in traffic light colours to provide a memory aid as to you selection. These screens come in 96 deepwell blocks so can be used directly on our Honeybee 963 crystallisation robot (Click on the name to download a data sheet and instructions on how to use.)

If you obtain crystals in any of the initial hits which are not immediately suitable for X-ray diffraction analysis (e.g. clusters of small needles) seek advice on what to do next, simply employing more screens is not the best way to proceed.

Initial Green Screens:

These 2 screens encompass the vast majority of conditions in which protein crystals have been grown and are a logical and limited first step

• JCSG+: (A Sparse matrix screen)
• PACT Premier: (Systematic analysis of the effect of pH and anions and cations)

Intermediate Yellow Screens:

• Morpheus: A 96 condition 3D protein crystallization screen with original chemistry incorporating a range of low molecular weight ligands found ordered in ~33,000 deposited structures.

Clear Strategy Screen:

• pH 5.5 & 6.5 / pH 7.5 & 8.5 (what is the pI of your protein? This screen consists of 48 conditions that in which you decide on the pH range to screen, thus a 96 deepwell plate covers 48 conditions at 2 different pHs

Later Red Screens:

• MDL Structure Screen
• Hampton I & II
• Emerald Wizard Screen I & II
• Newcastle Screen
• Anything else you can think of ...screen