Princeton University   |   Department of Molecular Biology

LuxP:LuxQ crystals
Crystals of the LuxP:LuxQ complex
See: Neiditch et al. (2005)

The most successful crystallization experiments start with chemically and conformationally homogenous macromolecules - your odds of success decline as the purity drops below 90% or if your molecule contains extensive regions of flexible structure. We can help you with purification protocols and suggest strategies with designing fragments for crystallization trials.

We treat everything on a case-by-case basis but you'll typically need macromolecule at concentrations in the 5–20 mg/ml range in 50 mM buffer (no phosphate, please) and 150–500 mM salt. You'll want 40 µl for each tray - 96-well trays at 300 nl per drop or 24-well trays at 1.5 µl per drop work out to be about the same amount of solution. We rarely solve a structure off less than 10 trays, although some people have better luck with this than others.

Initial crystallization experiments are a pre-formulated series of screens that have historically shown propensity for producing protein crystals. The facility operates an Art Robbins Phoenix crystallization robot which is particularly efficient at setting up crystallization trials in a compact 96-well format, and we possess a wide range of the most productive crystallization screens. The crystallization robot can create crystallization drops with sub-microliter volumes at the rate of several hundred per hour. A short initial training session is required to operate the instrument but we have a whole series of customizable existing protocols to cover experimenters' needs.

Art Robbins Phoenix Crystal Robot
Art Robbins Phoenix crystallization robot

We also stock larger format 24-well plates for optimizing any crystal hits that arise in the first round of screening: sitting drop plates in the CrysChem format; hanging drop plates in the VDX format. While these consume more material per drop they are also more suitable for generating crystals of a size appropriate for X-ray data collection.