Table III.
Steady state kinetic parameters of different homologs of BaiE from key Clostridium sp. associated with secondary bile acid synthesis†
| Homolog | Kinetic Parameters | Substrates
|
|
|---|---|---|---|
| 3-oxo-Δ4-CDCA | 3-oxo-Δ4-CDC-CoA | ||
| BaiE_15053 | kcat (sec−1) | 18.6(0.6) | 12.6 (0.6) |
| KM (μM) | 21.0 (2.0) | 11.4 (1.9) | |
| kcat/KM (μM−1 sec−1) | 0.9 | 1.1 | |
|
| |||
| BaiE_13275 | kcat (sec−1) | 4.4 (0.1) | 22.2 (2.6) |
| KM (μM) | 25.0 (1.8) | 208.0 (40.0) | |
| kcat/KM (μM−1 sec−1) | 0.2 | 0.1 | |
|
| |||
| BaiE_35704 | kcat (sec−1) | 18.0 (0.9) | 15.0 (0.2) |
| KM (μM) | 11.0 (1.9) | 1.2 (0.2) | |
| kcat/KM (μM−1 sec−1) | 1.6 | 12.5 | |
|
| |||
| BaiE_12708 | kcat (sec−1) | 24.0(1.4) | 98.0 (2.7) |
| KM (μM) | 9.9 (2.1) | 4.0 (0.56) | |
| kcat/KM (μM−1 sec−1) | 2.4 | 24.5 | |
†
Steady state kinetic parameters were analyzed at substrate concentrations ranging beyond and below the respective KM values. Reaction was monitored by the formation of product 3-oxo-Δ4,6-lithocholic acid and 3-oxo-Δ4,6-lithocholyl-CoA for respective substrates at wavelength 297 nm. Values in parentheses indicate standard error.
BaiE_15053: BaiE from Clostridium hylemonae DSM15053
BaiE_13275: BaiE from Clostridium hiranonis DSM13275
BaiE_35704: BaiE from Clostridium scindens ATCC35704
BaiE_12708: BaiE from Clostridium scindens VPI12708