Prior to starting the crystallization process, researchers must have pure macromolecular samples. The best macromolecular samples for crystallization experiments are homogenous in content, chemistry and conformation. For proteins, recombinant methods are most often employed, but there is a bewildering number of alternative protocols to consider before starting.
Realizing that some investigators' labs are insufficiently equipped — and that investigators may have limited expertise — the Structural Biology Facility provides infrastructure, methodology, advice and some supplies to produce the samples needed. The facility can also be a collaborative resource for projects that require pure, intact protein for experimental purposes other than crystallography.
Over the past two decades, projects have expressed and purified numerous functional proteins from bacteria, yeasts and insect cells. Because sample production is often difficult, many different technologies and strategies have been employed to optimize successful yield along with ease, speed, cost and versatility.
Higher throughput protein expression methods developed by structural genomics centers are now being implemented, as crystallization results using only one sample are more uncertain. Additionally, completely novel protocols are being developed for easier and less expensive expression or co-expression of difficult-to-make eukaryotic proteins.
With samples in hand, researchers can move on to crystallization.