Crystallization Unit

PROTEIN SAMPLE REQUIREMENTS

To increase the chances of crystallization, macromolecular samples should ideally be highly pure, concentrated and monodispersed.
A good practice to estimate sample's purity is to load 5-10 μg of protein onto an SDS-PAGE, and verify that few secondary bands are present after Coomassie staining. For initial screening, we advise to provide a sample at the highest concentration compatible with solubility (measured by absorbace reading at 280 nm), possibly not less than 10 mg/ml.
Performing a Size Exclusion Chromatography experiment before submitting the sample for crystallization will provide good evidence that it consists of an homogeneous population of proteins or complexes, all with the same stoichiometry, conformation, post-translational modifications etc (i.e. that is monodispersed).

For more information about sample preparation, do not hesitate to contact us.