TABLE 2.
Mutation sites, t50 values, and specific activities for mutants with improved thermostability
| Enzymea | Sourceb | Substitution(s) in mutant | t50 (min)c | Activity (U mg−1) |
|---|---|---|---|---|
| WT | 10 | 1,870 | ||
| 2B9 | 1st | S271G | 35 | 3,001 |
| 1G4 | 1st | S271G, N289H | 50 | 3,079 |
| 1D2 | 1st | N227S, S271G, K313R | 50 | 1,758 |
| 3F6 | 1st | T178A, S233C | 45 | 1,121 |
| 115 | 1st | E124I | 30 | 1,304 |
| 3F7 | 1st | S271G, S308L | 40 | 1,997 |
| 3B9 | 1st | R72S, S271G | 40 | 1,316 |
| T178A | SDM | T178A | 40 | 836 |
| B7 | 2nd | S271G, N289H, A254T | 120 | 2,385 |
| D11 | 2nd | S271G, N289H, N186D | 100 | 2,003 |
| E2 | 2nd | S271G, N289H, N186D, I211V | 150 | 2,195 |
| EA | CM | N186D/I211V/A254T/S271G/N289H | 240 | 2,305 |
| EAT | CM | T178A/N186D/I211V/A254T/S271G/N289H | 840 | 901 |
| EAE | CM | E124I/N186D/I211V/A254T/S271G/N289H | 900 | 1,130 |
| EAET | CM | E124I/T178A/N186D/I211V/A254T/S271G/N289H | 1,400 | 293 |
a
WT, wild type.
b
1st and 2nd indicate the first and the second rounds of ep-PCR, respectively. SDM, site-directed mutagenesis; CM, combined mutagenesis.
c
The t50 values were determined at 50°C.