The C6 webtool aims to simplify the crystallisation landscape by showing the relationship between the different screens, and help you select an appropriate subset of the screens that we have available.
The more you know about your protein, the better initial choice you can make.
Available Screens: C6 provides a list of all the currently available screens you can choose from, and a breakdown on the individual contents of each well. This is a great tool if you’re looking for a very specific commercial screen to use immediately.
Searching for Conditions: You can use the C6 webtool to find screens that contain a condition that you know your protein likes (or something very close). For example the literature may suggest that similar proteins have crystallised rapidly in ammonium sulfate and low MW PEGs, using the C6 Webtool you can search for all screens that contain conditions with these chemicals.
The most powerful tool in C6 allows you to look at Screen Similarity. It provides both a visual and numeric representation of how similar one screen is to any other, which can help you to screen a wider space of conditions (less similar screens) or to find an alternative screen to one that is not currently available (very similar screens).
We use the concept of similarity intuitively, not only in crystallisation, but in all aspects of our lives. With this idea, we can look for patterns, for example ‘all citrus fruits are acidic’, and make inferences from those patterns – ‘lemon juice could be a substitute for orange juice’.
The C6 comparison tool showing screens which are similar to JSCG+; the visual distance is a true metric, with numeric data available below
If we add a distance measure between similar objects, we can then rank them: ‘limes are more acidic than oranges’, and refine our inferences: ‘orange juice would be better substituted for lemon juice than lime juice’. Fundamentally the C6 webtool assigns a quantitative similarity value between any two crystallisation conditions, thus allowing one to make inferences based on the idea of similarity. Even though the fundamental measure in the C6 webtool is between two crystallisation conditions, we use this to build up a robust measure of similarity between screens.
Reference: Newman J. Fazio V. Lawson B. & Peat T. 2010. The C6 Web Tool: A Resource for the Rational Selection of Crystallization Conditions. Crystal Growth & Design. 12219-12223.