Table 1.
| Michaelis-Menten Kinetics |
P. putida methionine-γ-lyase | ||
|---|---|---|---|
|
| |||
| Substrate | kcat ( s−1) | KM (mM) | kcat/KM (s−1 mM−1) |
| l-methionine | 20 ± 0.4 | 0.34 ± 0.03 | 59 ± 6 |
| l-cystathionine | nd | nd | nd |
| l-cysteine | 6.5 ± 0.2 | 1.1 ± 0.1 | 6 ± 0.7 |
| dl-homocysteine | 86 ± 3 | 2.9 ± 0.2 | 30 ± 3 |
|
| |||
| Substrate | Human cystathionine-γ-lyase | ||
|
| |||
| l-methionine | nd | nd | nd |
| l-cystathionine | 3.7 ± 0.2 | 0.40 ± 0.07 | 9 ± 2 |
| l-cysteine | 0.15 ± 0.02 | 0.79 ± 0.30 | 0.2 ± 0.1 |
| dl-homocysteine | 0.35 ± 0.02 | 1.7 ± 0.30 | 0.21 ± 0.04 |
|
| |||
| Substrate | Human cystathionine-γ-lyase-NLV | ||
|
| |||
| l-methionine | 7.9 ± 0.4 (≥106 *) |
14 ± 1.5 | 0.56 ± 0.07 |
| l-cystathionine | 0.54 ± 0.02 | 0.83 ± 0.1 | 0.65 ± 0.07 (-14) |
| l-cysteine | 2.7 ± 0.1 | 0.84 ± 0.1 | 3.2 ± 0.3 (16) |
| dl-homocysteine | 2.6 ± 0.1 | 0.9 ± 0.1 | 2.8 ± 0.3 (13) |
nd = not detected, ( ) = fold change from hCGL.
*
estimated from DTNB assay limits. All reactions were performed at 37 °C with the MBTH assay.