Crystallization of β-Galactosidase Does Not Reduce the Range of Activity of Individual Molecules

By use of a capillary electrophoresis-based procedure, it is possible to measure the activity of individual molecules of β-galactosidase. Molecules from the crystallized enzyme as well as the original enzyme preparation used to grow the crystals both displayed a range of activity of 20-fold or greater. β-Galactosidase molecules obtained from two different crystals had indistinguishable activity distributions of 31 600 ± 1100 and 31 800 ± 1100 reactions min-1 (enzyme molecule)-1. This activity was found to be significantly different from that of the enzyme used to grow the crystals, which showed an activity distribution of 38 500 ± 900 reactions min-1 (enzyme molecule)-1.