Structural Medicine     

Protein Crystallography Course


Initial screening may be done by hanging drop vapour diffusion (protocol).

Commercially Available Screens

Hampton Research
Hampton Research make and distribute products for protein crystallization. Their kits have become the most common starting points for crystallizing previously uncrystallized protein.

Douglas Instruments have released a table for sorting the order of the Hampton conditions by type of precipitant.

For recording the data from the Hampton screens you can use Marko Hyvonen's tables.

They are based on the sparse matrix screening protocol.

Hampton also make Grid Screens for popular precipitants.

Molecular Dimensions
Molecular Dimensions make the same kits, but the conditions are ordered by pH. 3D Structure Screen
The 3D Structure Screen is a sparse matrix screen which givess 24 "nucleation" conditons and 24 "backed-off" conditions. In this kit the crystal growth trial is performed as a two step method. Firstly conditions are set up for nucleation and then the drops on their coverslips are transferred to wells with a lower concentration of precipitant for crystal growth. Saradakis & Chayen (Protein Science (2000), 9:755-757)

Clear Strategy Screens I & II
Clear Strategy Screens allow you to use the information already collected about the structure and activity of your protein to control folding homogeneity. The conditions are formulated at 90% of their final volumes allowing the starting pH to be changed depending upon your prior knowledge of the protein’s properties (e.g. isoelectric point, solubility/stability, previous experience with related proteins). The formulation principles also enable easy interpretation of results and simple planning of further experiments. Developed by Dr A M Brzozowski and J Walton at the University of York.

Emerald Biostructures
Emerald Biostructures produce four kits for protein crystallization. They are sparse matrix screens like the Hampton Screens but have different conditions. Developed by Steve L. Sarfaty and Wim. G. J. Hol.

Jena BioScience
Jena BioScience produce 10 screening kits covering 240 conditions. Their compositions result from data mining of several thousands of crystallized proteins. JBScreen represents the statistically most successful buffers that yielded protein crystals suitable for X-ray diffraction. (References: Jancarik & Kim (1991) J. Appl. Cryst. 24:409, Gilliland et al. (1994) Acta Cryst. D50:408, & Cudney et al. (1994) Acta Cryst. D50:414 )

Other Screens

Other screens have been published but are not commercially available

The Footprint screen includes the protein concentration as a parameter in the screen and maps out phase space.

The Reverse Screen can be used when something is known about the crystallization conditions for the class to which the protein belongs. You make a guess of what are likely crystallization conditions rather than screening from scratch.
Reverse screening. E. A. Stura, A. C. Satterthwait, J. C. Calvo, D. C. Kaslow and I. A. Wilson. Acta Cryst. (1994). D50, 448-455

DIY Screens


If your protein comes out of solution at low salt concentrations (i.e. needs a small amount of salt to stay in solution), desalting may be an alternative to salting-out.

Dialysing your protein against water is a good starting point.

Crystallizability is inversely proportional to biological interest
Murphy's crystallization law

© 1999-2005 Airlie J McCoy, University of Cambridge. All rights reserved.

Last updated: 7 June, 2005