Crystallization of two bacterial enzymes on an unmanned space mission

We have grown crystals of two bacterial enzymes, thermolysin from Bacillus thermoproteolyticus and a novel 23 kD lysozyme from Streptomyces coelicolor, on the unmanned COSIMA-2 space mission. The crystals obtained under microgravity conditions were compared with crystals grown in a ground control experiment using identical hardware, and with those obtained in 'hanging drops' in the laboratory. For both enzymes, the space-grown crystals tended to be longer but thinner than their terrestrial counterparts. The diffraction properties of each type of crystals were assessed by collecting nearly complete diffraction data sets using an area detector. Space-grown crystals of the enzymes showed much weaker diffraction than both the ground control and the laboratory-grown crystals. Possible reasons for this are discussed.