Table 3.
Effect of mutations in sprE on chitinase activity
| Strain | Chitinase activitya |
|
|---|---|---|
| Extracellular | In cell extracts | |
| FJ1 (wild type)b | 223 (54) | 241 (32) |
| FJ149 (sprE mutant)b | 0 (0) | 272 (51) |
| FJ149 complemented with pNap2 | 234 (86) | 279 (50) |
Chitinase activities were determined using the synthetic substrate 4-MU-(GlcNAc)2. Equal amounts of each sample, based on the protein content of the original cell suspension, were incubated with 10 nmol of 4-MU-(GlcNAc)2 for 4 h at 37°C, and the amount of 4-MU released was determined by measuring fluorescence emission at 460 nm following excitation at 360 nm. Activities in the cell-free supernatants (extracellular chitinase) and in cell extracts are indicated as pmol 4-methylumbelliferone released per μg total protein in the original cell suspension. Numbers in parentheses are standard errors calculated from three measurements.
Strains without pNap2 carried control vector pCP23 so that all cultures could be grown under identical conditions in the presence of tetracycline.