Proposal

It is therefore proposed to attempt the crystallization of a soluble form of recombinant human FceRII under microgravity conditions for structure solution by X-ray crystallography, and to crystallize the soluble recombinant human FcgRIII to attempt improving the existing x-ray crystallographic data of this receptor.

Experimental Details Experiment SPC

Hardware requirements:

Refrigerator-Thermostat Cryogen-03M to transport crystallization devices to ISS

Luch-2 and Biocryst-M to activate crystal growth.  The crystallization cassette should contain 12 crystallization units (standard size is 98 x 48 x 24 mm).  One set of cassettes, containing 6 cassettes will be used to screen various precipitant conditions for the two proteins (a total of 72 experiments is thus planned, 12 x 6 = 72).

A thermostat to transport cassettes back if crystals grow on mission (Byokont-T).

Method:

At ground level: Two (2) weeks prior to launch - Protein drops (~ 2 microlitres) are placed into the crystallization chambers of a cassette.  Precipitant solution (0.5 millilitres) is added to the precipitant chamber of the cassette.  The crystallization cassette (device) is sealed to prevent vapour diffusion.  The sealed cassettes are transported to launch site and stored at 4ºC.

Launch date - A set of cassettes (6 cassettes in total) is transported at 4ºC to the ISS.  On the ISS - In the crystallizer on ISS, the cassette seals are broken to activate crystal growth by vapour diffusion.  Crystal growth occurs at 20ºC.  Should crystals grow on the mission, the cassettes are re-sealed and transported back to earth at ambient temperature around 20ºC.  Note, Russian crystallizers to be transported to ISS in February 2002.  Time required on ISS: one (1) hour on day 3 or 4, another hour on final day of mission.

At ground level - Crystals will be analysed by X-ray crystallography in Munich, Germany to measure the quality of crystals and solve protein structures should the crystals be of high enough quality.