STATISTICAL DESIGN OF EXPERIMENTS FOR PROTEIN CRYSTAL-GROWTH AND THE USE OF A PRECRYSTALLIZATION ASSAY

Incomplete factorial designs have been used to crystallize all of the proteins the authors are now studying (tryptophanyl-tRNA synthetase, cytidine deaminase, and a manganese catalase). In each case they used a rudimentary microscopic examination to determine the experimental outcomes. From these data they have generated for each protein a ″factor profile″ showing the relative importance of the factors studied. In at least one case, the specific information in this profile lead to a substantial improvement in the crystals they were able to grow. Considerable potential power lies in the ability to feed information obtained from all experiments in an initial trial back into the design of subsequent improvements in crystal growth conditions.