Table 1.
Effects of pH on enzyme activity
|
Buffer |
pH |
Specific activity (U mg-1 total protein)a |
Total protein concentration (mg ml-1) b | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| GK | PGI | PFK | FBA | TIM | GAPN | iPGM | ENO | PK | MLDH | |||
| MES |
6 |
0.19 |
7.6 |
4.9 |
7.3 |
9.2 |
0.030 |
0.11 |
1.1 |
9.4 |
0.0026 |
8.6 |
| MES |
7 |
3.7 |
7.3 |
18 |
7.3 |
17 |
0.039 |
0.17 |
2.6 |
5.2 |
0.013 |
2.2 |
| HEPES |
7 |
2.9 |
2.3 |
8.8 |
6.9 |
13 |
0.036 |
0.20 |
3.1 |
4.5 |
0.019 |
1.7 |
| HEPES |
8 |
5.1 |
11 |
18 |
6.5 |
5.0 |
0.042 |
0.087 |
1.2 |
0.65 |
0.014 |
2.2 |
| Bicine |
8 |
4.5 |
16 |
15 |
4.0 |
2.1 |
0.035 |
0.078 |
1.3 |
1.0 |
0.011 |
2.7 |
| Bicine |
9 |
7.5 |
14 |
18 |
2.4 |
0.07 |
0.041 |
0.035 |
0.66 |
0.42 |
0.012 |
3.0 |
| CHES |
9 |
6.0 |
14 |
30 |
4.4 |
0.9 |
0.031 |
0.017 |
0.40 |
0.19 |
0.0095 |
4.1 |
| CHES | 10 | 2.6 | 6.1 | 10 | 4.6 | 2.3 | 0.0051 | 0.00075 | 0.10 | 0.047 | 0.0021 | 41 |
a The specific enzyme activities in the crude extract of recombinant E. coli were determined under standard assay conditions (50°C) at indicated pHs.
b The total protein concentration of the enzyme mixture (containing 0.01 U each of GK, PGI, PFK, FBA, and TIM, along with 0.02 U each of GAPN, iPGM, ENO, PK and MLDH) was estimated.