TABLE 3.
Specific activities and release of SodC enzymes by osmotic shock
| Enzymea | Strainb | Sp act (U/mg)c | SOD activity (U/ml/OD600) (%)c
|
|
|---|---|---|---|---|
| French press | Osmotic shock (%) | |||
| Multicopy enzymes in E. coli | ||||
| SodCI | E. coli pMC101 | 53.6 | 23.3 | 0.21 (0.9) |
| SodCII | E. coli pRK101 | ND | 11.0 | 10.3 (94) |
| SodCI C−5T | E. coli pRK104 | ND | 13.9 | 0.08 (0.6) |
| (SodCII1-25 SodCI26-157)hyb | E. coli pBK101 | 68.1 ± 9.7 | 6.4 ± 0.4 | 0.004 ± 0.0 (0.06) |
| (SodCI1-26 SodCII27-153)hyb | E. coli pBK102 | 24.4 ± 0.3 | 2.5 ± 0.3 | 2.7 ± 0.1 (108) |
| SodCI Y87E Y109E | E. coli pRK106 | 48.7 ± 10.4 | 22.1 ± 7.8 | 15.3 ± 0.0 (69) |
| Single-copy enzymes in Salmonella | ||||
| SodCI | Serovar Typhimurium | 1.0 ± 0.3 | 0.09 ± 0.02 | 0.005 ± 0.00 (5.6) |
| SodCII | Serovar Typhimurium | 3.6 ± 0.6 | 0.36 ± 0.01 | 0.30 ± 0.08 (83) |
| (SodCII1-25 SodCI26-157)hyb | Serovar Typhimurium | 0.5 ± 0.3 | ND | ND |
| SodCI Y87E Y109E | Serovar Typhimurium | 0.9 ± 0.1 | 0.11 ± 0.00 | 0.07 ± 0.02 (64) |
a
All strains produce only the indicated SOD.
b
Strains used are either E. coli AS391 containing the indicated plasmid or serovar Typhimurium strains JS460, JS459, JS679, and JS680.
c
Data are from single but repeatable experiments (n = 3) where means of the results ± standard deviations are given. Numbers in parentheses indicate the percentage of enzyme released by osmotic shock, and the amount of enzyme released by a French press is considered 100%. ND, not determined; OD600, optical density at 600 nm.