You will need:

• Your protein
• A Costar spin-X centrifuge tube filter
• The screen, e.g. Hampton's Crystal Screen 1
• Hampton's Greased VDX plate or equivalent
• Hampton's 22mm Siliconized Thick Circle cover slides or equivalent
• 2 microlitre or 10 microlitre pipette
• 1ml pipette

• Your protein should be at about 10mg/ml in a weak buffer, e.g. 5mM Hepes
• If your protein will only concentrate to lower concentrations, start at lower concentration
• If your protein requires additives to stay in solution or to stay monodispersed, e.g.150mM NaCl or DTT, include these
• Label your concentrated protein with a batch number. Differences in the purification protocols may later relate to irreproducibility in crystallization
• Filter your protein
• Label your tray before you set up the trials, on the base not on the cover - covers can get mixed up!
• Add 0.5 - 1ml of each trial solution to the wells in turn. Use a positive displacement pipette if you are mixing viscose solutions in the well rather than pipetting from a premixed solution
• Take 6 cover slips and put them in a row
• Pipette out 2 microlitres of protein into each of the 6 coverslips
• Pipette out 2 microlitres of each of the 6 wells onto the protein drops
• Turn the coverslips over onto the wells and make sure they are sealed
• When you have finished the tray look at the drops under the microscope
• Note which drops have precipitated immediately
• Set up new drops at half the precipitant concentration for those that have precipitated
• Note any "bits" in the drops (threads, dirt, chips on the slide)
• Put the tray in a temperature controlled environment where it will not be disturbed
• Check daily for a week
• Keep checking regularly for at least a month
• Check before you throw it out

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

Last updated: 7 June, 2005