Setting higher standards requires the proper tools.
Like our new crystallization screen redundancy poster.

Since the initial description of sparse matrix crystallization screening by Jancarik and Kim in 1991 (which led to the development of Crystal Screen 1 and 2), many different screens for the crystallization of macromolecules have been developed(1). By our last count, there exist over 200 commercially available crystallization screens available from various companies, including approximately 50 screens available from Anatrace, Molecular Dimensions, and Microlytic.  These include screens specific for the crystallization of nucleic acids, protein complexes, membrane proteins, kinases, and various other specific macromolecules. 

                                 

With this sheer number available crystallization screens, how do you choose a set of screens for your initial crystallization experiments? With the help of tools developed by Janet Newman and her lab at CSIRO in Australia, we aim to make that question easier to answer.

 
The C6 – Comparison of Crystallization Conditions @ C3 web server contains a number of useful tools for the analysis of commercially available and custom crystallization screens(2). One tool on this server allows for the comparison of any two crystallization screens by taking into account the chemical composition of each screen (buffer, salt, precipitant, etc). When two screens are compared, the result is a score between 0 and 1, where a score of 0 represents complete screen identity, and a score of 1 represents complete screen dissimilarity. A score of 0.3 or less indicates that the two screens are significantly similar to one another. 
 
Using the C6 server, we performed a pairwise comparison of all commercially available screens and created a poster summarizing the data from the most commonly used screens. For each screen pair, the level of chemical similarity is represented by one of four colors, with red indicating the two screens are significantly similar to one another (score < 0.3), and purple indicating that the two screens are dissimilar from one another (score between 0.75 and 1.0). Additionally, if there are conditions that are exactly the same between two screens, the number of identical conditions is indicated.
 
Using this poster, you will be able to quickly choose a set of screens that cover the most chemical space, and reduce redundancy in your crystallization screening. Do you already have your favorite set of initial screens? Then use this poster to choose additional screens if your first pass screening does not yield crystals. 
 
To have a poster to hang in your lab, send us an e-mail, and we’ll send one over to you!  

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