by Peter Nollert
July 21, 2009 08:52
After days, weeks or months of work in the lab you've got the precious vial of protein sample to set up crystallization trials with. What are things to generally avoid doing with such precious liquids? Here's my shortlist of favorite ways to spoil protein samples:
1. Introduce proteases by not wearing gloves, using dirty storage vials, leaving the protein sample in an open container or expose to dust.
2. Generate a protein foam by vigorous vortexing / shaking, repeated triturating or by fast stirring in an Amicon pressure concentrator.
3. Let protein sample age by leaving the solution on the bench for hours or days before subjecting to protein crystallization.
4. Precipitate by freezing a single volume of sample and thaw slowly on ice, freeze and slowly thaw, over and over an over again.
5. Heat denature by warming up sample for extended periods of time in hands, pockets of pants or shirt.
6. Contaminate with crystallization reagents by re-using pipetting tips and accumulating precipitiation reagents via transfer from the screen to the protein sample vial.
7. Stimulate non-enzymatic proteolysis by keeping mM concentration of metal ions in the buffer.
8. Over concentrate in the centrifugation concentrator device until the sample has vanished or dried out.
9. Support aggregation by keeping precipitate in the sample.
10. Photo- or heat denature by exposure to intense direct sunlight for long periods of time.
Your precious samples deserve better,
Peter