Table 2.
Experimental parameters for a RNA Raman crystallography experiment
RNA crystal | Raman microscope system | ||
---|---|---|---|
Size | Minimum is 30 μm edge; typical is 100–300 μm | Excitation source | 647.1 nm Kr+ laser |
Quality | Stable to changes of experimental conditions (e.g. pH, ions, …) | Laser power | 50–100 mW |
Reservoir solution | Stabilization buffer: 20 mM MgCl2, 2 mM spermine, 50% MPD, 50 mM buffer | Microscope objective | 50× (or 20×) long- focal-length |
Hanging drop | ~5 μL stabilization buffer | Operation mode | Nonconfocal mode |
Symmetry | High symmetry is less orientation-dependent (e.g. cubic) | Data collection time | 100 s (=10 accumulations for 10 sec each) |
Resolution | Low resolution (e.g. 5 Å) crystals work well | Operation temperature | Room temperature |
Temperature | Crystal is in hanging drop at ambient temperature (i.e. no cryo- conditions used) | Detector | Charge-coupled device at −70 °C |