French grow Thaumatin Crystals in Space!! Would hope XOMA could license this product, since there seems to be an interest in it.
Crystallisation of RNA Molecules Under Microgravity Conditions
Principal Investigator: Prof. Volker Erdmann, Free University of Berlin, Germany
Ribonucleic acid (RNA) molecules have diverse biological roles, which include carrying genetic information or amino
acids to the ribosomes during protein synthesis and participating as constituents of the ribosomes as they carry out
biological functions. Also, RNA molecules may exhibit enzymatic activities. Because of the large mass of its molecules,
it has been extremely difficult to crystallise RNA molecules on Earth.
Results:
Of the five crystallisation experiments performed, three yielded crystals. The crystals obtained were larger in size and
more numerous than those obtained in simultaneous ground-control experiments. The largest space-grown crystals had a
length of 0.7mm. In the ground-control experiments, only two chambers yielded crystals. These were smaller in size and
less numerous than those grown in space. The largest crystal had a length of 0.45 mm. All crystals were analysed by
synchroton radiation at the DESY facilities in Hamburg, Germany, six days after landing. Both space and ground-
control crystals exhibited a resolution of 13 Å.
Microgravity Crystallisation of Thermophilic Aspartyl-tRNA Synthetase and
Thaumatin
Principal Investigator: Dr Richard Giegé, CNRS, Strasbourg, France
Investigators want both to continue and expand the IML-2 crystallisation studies on thermophilic aspartyl-tRNA
synthetase and to crystallise the plant sweetening protein, thaumatin. While both proteins are biochemically stable and are
purified easily, they also have significant structural and behavioural differences; therefore, they make interesting subjects
for comparative crystallography studies. In addition, thaumatin tastes extremely sweet when consumed by humans. Since
it appears to be non-toxic, non-carcinogenic, and low in calories, it may be a strong substitute for common table sugar.
Preliminary Conclusions
The quality of the space crystals obtained in this study is compared directly to those grown under ground conditions at
the same time. Space and Earth-grown crystals were prepared from the same protein preparation and have undergone the
same manipulation, so that the relative comparisons between crystals grown in space and on Earth can be significant.
Thaumatin crystals grown in the DIA reactors in space were observed to grow much bigger with significantly less
nucleation than the corresponding ground controls. This observation is most striking and is statistically significant, since
this phenomenon has been observed in all the reactors containing thaumatin.
The diffraction limits of the crystals grown in space were about the same as those grown on Earth; however, the
mosaicity of space-grown crystals was less than that of the ground controls.
Very small crystals were obtained for AspRS, but these crystals were not big enough for analysis. Most reactors
containing this enzyme did not crystallise. Investigators speculate that the flight delay may have contributed to the
denaturation of the protein, thus hindering its normal crystal growth.
Overall, results indicate a significant difference between quality and size of thaumatin crystals that are grown on Earth
and those that are grown in space. |
