Cryocrystallography

 

Cryocrystallography has become an essential and routine tool in structural biology over the last decade as a result of observation of great reduction in radiation damage to protein crystals during X-ray diffraction experiments at cryotemperatures (Low et al., 1966; Haas and Rossmann, 1970). As radiation damage was becoming a limiting factor in the utilization of synchrotron radiation sources in the early 1990s, a simple loop-mounting method was developed for cryocrystallography by former BioCARS staff scientist Tsu-Yi Teng (Teng, 1990). The method is now widely and routinely used by the majority of protein crystallographers at synchrotron and laboratory X-ray sources.

Equipment and tools for cryocrystallography are offered to users in all three BioCARS experimental stations.

  • Low, B. W., Chen, C. C. H., Berger J. E., Singman, L and Pletcher, J. F.
    (1966) PNAS USA 56, 1746-1750
  • Haas, D. J. and Rossmann, M. G.
    (1970) Acta Cryst. B26, 998-1004
  • Teng, T.-Y. (1990)
    J. Appl. Cryst. 23, 387-391

 


 

Loop Mounts And Cryo Tools

BioCARS supports Yale and Hampton style loop mounts. The range of the BioCARS goniometer Z-translation is 24 mm. Cryo pin lengths of 15 to 25 mm can be accommodated (lengths are measured from the loop to the pin base). Cryo loops are conveniently mounted on BioCARS diffractometers using horizontal (Ω=0°, K=0°) or inclined geometry (Ω=0°, K=60°).

 

Tools and Gadgets:

BioCARS provides some tools for cryocrystallography such as 4l LN2 transfer dewars, cryo-PPE (gloves and goggles), cryo wands, cryo tongs, vial clamps, cryo canes, low and tall dewars and various strength magnetic bases. A box with a set of Hampton cryo tools can be signed out from BioCARS staff. Users are encouraged to bring their own favorite cryo tools and gadgets.

 

 

Crystal Coolers

 

Cooler Temperature range (K) Cold gas flow rate (l/min) Nozzle size dia. (mm)
Oxford Instrument
Cryojet
100 - 300 4 - 10 7.2
Oxford Cryosystems Cryostream 100 -300 5 5.0

 

Oxford Instrument CryoJet

CryoJet Procedures (Staff only)

The new boil-off design CryoJet crystal cooler supplies cold nitrogen gas by evaporating liquid nitrogen with a heater at the end of CryoJet dewar leg. Cold boiled-off gas starts from the bottom of the Oxford 75 liter dewar. The Transfer Tube transports the gas to the heat exchanger in the ColdHead, where its temperature is regulated by the programmable ITC503 Cryojet controller. This design reduces the chance of ice blockage, which happens often in the pumped design coolers. The lowest reachable temperature however is higher than for the pumped design coolers. The warm gas shield at the nozzle is also supplied by a boiled-off gas line. It is important to keep the warm gas flow rate about the same as the cold gas flow rate (4 l/min).

 Old Cryojet Cooler

  New Cryojet Cooler

 

Oxford Cryosystems CryoStream

Cryostream Procedures (Staff only)

The CryoStream crystal cooler draws liquid nitrogen from a Taylor Wharton 35DL dewar through the Diaphragm Pump and the Supply Line to the Heat Exchanger.
The liquid is evaporated in the Heat Exchanger, dried by the Line Drier and fed back to the ColdHead. The gas is then recooled and its temperature controlled by the Programmable Temperature Controller via the Heater Coil.

The warm gas shield at the nozzle is supplied by the BioCARS cryostat nitrogen line. The flow rate of the warm gas can be adjusted on the Cryostat Gas panel in the hutch. It is important to keep the warm gas flow rate about the same as the cold gas flow rate (5 l/min).

 Cryostream Cooler

  Cryostream Cooler

 


 

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